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All questions of Magnetism and Matter for NEET Exam
Which combination of magnetic field lines and poles shows two magnets repelling each other?- a)
- b)
- c)
- d)
Correct answer is option 'B'. Can you explain this answer?
Which combination of magnetic field lines and poles shows two magnets repelling each other?
a)
b)
c)
d)
|
Lavanya Menon answered |
- The discovery that one particular pole of a magnet orients northward, whereas the other pole orients southward allowed people to identify the north and south poles of any magnet.
- It was then noticed that the north poles of two different magnets repel each other, and likewise for the south poles. Conversely, the north pole of one magnet attracts the south pole of other magnets.
- This situation is analogous to that of electric charge, where like charges repel and unlike charges attract. In magnets, we simply replace the charge with a pole: Like poles repel and unlike poles attract.
A bar magnet of magnetic moment 1.5 J/T lies parallel to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?- a)-0.3J
- b)0.23J
- c)0.0J
- d)0.3J
Correct answer is option 'B'. Can you explain this answer?
A bar magnet of magnetic moment 1.5 J/T lies parallel to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?
a)
-0.3J
b)
0.23J
c)
0.0J
d)
0.3J
|
Preeti Iyer answered |
Answer :-
Solution :- torque when 
=180°
=180°
= 1.5 × 0.22 × sin 180°
= 0.33 × 0 = 0 Nm
A toroid wound with 60.0 turns/m of wire carries a current of 5.00 A. The torus is iron, which has a magnetic permeability of μm=5000μ0 under the given conditions. H and B inside the iron are- a)340AT/m,2.88T
- b)340AT/m,1.88T
- c)380AT/m,1.98T
- d)300AT/m,1.88T
Correct answer is option 'D'. Can you explain this answer?
A toroid wound with 60.0 turns/m of wire carries a current of 5.00 A. The torus is iron, which has a magnetic permeability of μm=5000μ0 under the given conditions. H and B inside the iron are
a)
340AT/m,2.88T
b)
340AT/m,1.88T
c)
380AT/m,1.98T
d)
300AT/m,1.88T
|
Neha Sharma answered |
B=B0+Bm
= μ0nI+ μmnI
=nI(μ+ μm)
=60x5(5000μ0+ μ0)
B=300(5001μ0)
B=1.88T
H=B/μm
=300x5001μ0/5000μ
=300AT
= μ0nI+ μmnI
=nI(μ+ μm)
=60x5(5000μ0+ μ0)
B=300(5001μ0)
B=1.88T
H=B/μm
=300x5001μ0/5000μ
=300AT
When the switch is closed a magnetic field is produced by the coil. Which answer shows the shape of the field?- a)
- b)
- c)
- d)
Correct answer is option 'B'. Can you explain this answer?
When the switch is closed a magnetic field is produced by the coil. Which answer shows the shape of the field?
a)
b)
c)
d)
|
Anand Kumar answered |
Ya it's B ....
Emerges from one side and enter from another side...
Emerges from one side and enter from another side...
If the susceptibility of a metal at saturation is 4500, then what is the permeability of this metal at saturation?- a)5.684 X 10-4 T-m/A
- b)5.654 X 10-3 T-m/A
- c)5.654 X 10-7 T-m/A
- d)5.658 X 10-5 T-m/A
Correct answer is option 'B'. Can you explain this answer?
If the susceptibility of a metal at saturation is 4500, then what is the permeability of this metal at saturation?
a)
5.684 X 10-4 T-m/A
b)
5.654 X 10-3 T-m/A
c)
5.654 X 10-7 T-m/A
d)
5.658 X 10-5 T-m/A
|
Anaya Patel answered |
μr=μ/μ0
μ= μr x μ0
μ=4500 x 4πx 10-7
μ=56520x10-7
μ=5.652x10-3
μ= μr x μ0
μ=4500 x 4πx 10-7
μ=56520x10-7
μ=5.652x10-3
Which of the following statements about earth's magnetism is correct- a)The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south-west to the north-east.
- b)The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south-east to the north-west.
- c)The earth behaves as a magnet with the magnetic field pointing approximately from the geographic east to the west.
- d)The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south to the north.
Correct answer is option 'D'. Can you explain this answer?
Which of the following statements about earth's magnetism is correct
a)
The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south-west to the north-east.
b)
The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south-east to the north-west.
c)
The earth behaves as a magnet with the magnetic field pointing approximately from the geographic east to the west.
d)
The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south to the north.
|
Hansa Sharma answered |
According to recent researches the magnetic field of earth is considered due to a large bar magnet situated in earth's core.
It is considered that the north pole of this large magnet is situated at the geographical south of earth and vice versa and as the magnetic field due to a bar magnet is from north pole to south pole of the maget thus the earth's magnetic field is considered from geographical south to geographical north which are respectively north and south poles of the bar magnet.
It is considered that the north pole of this large magnet is situated at the geographical south of earth and vice versa and as the magnetic field due to a bar magnet is from north pole to south pole of the maget thus the earth's magnetic field is considered from geographical south to geographical north which are respectively north and south poles of the bar magnet.
What kinds of materials are used for coating magnetic tapes?- a)Diamagnetic Materials
- b)Ferrites
- c)Electromagnet
- d)Paramagnetic materials
Correct answer is option 'B'. Can you explain this answer?
What kinds of materials are used for coating magnetic tapes?
a)
Diamagnetic Materials
b)
Ferrites
c)
Electromagnet
d)
Paramagnetic materials
|
Divey Sethi answered |
Ceramics are used for coating magnetic tapes in a cassette player or for building memory stores in a modern computer. Ceramics are specially treated barium-iron oxides and are also called ferrites.
A short bar magnet has a magnetic moment of 0.48 J/T .Magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on the axis has a direction and magnitude of .- a)1.06 G along S-N direction.
- b)0.96 G along S-N direction.
- c)0.86 G along S-N direction.
- d)0.76 G along S-N direction.
Correct answer is option 'B'. Can you explain this answer?
A short bar magnet has a magnetic moment of 0.48 J/T .Magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on the axis has a direction and magnitude of .
a)
1.06 G along S-N direction.
b)
0.96 G along S-N direction.
c)
0.86 G along S-N direction.
d)
0.76 G along S-N direction.
|
Tanuja Kapoor answered |
Here M=0.48JT−1,d=10cm=0.1m
On axis,
B= (μ0/4π)(2M/d3)=10−7×(2×0.48/0.13)=0.96×10−4T
On axis,
B= (μ0/4π)(2M/d3)=10−7×(2×0.48/0.13)=0.96×10−4T
The units of magnetic pole strength and magnetic dipole moment of a bar magnet are- a)A-m, JT-1
- b)JT-1, Am-1
- c)JT-1, Am
- d)Am-1, JT-1
Correct answer is option 'A'. Can you explain this answer?
The units of magnetic pole strength and magnetic dipole moment of a bar magnet are
a)
A-m, JT-1
b)
JT-1, Am-1
c)
JT-1, Am
d)
Am-1, JT-1
|
|
Anaya Patel answered |
The units of magnetic pole strength is (A-m) and magnetic dipole moment of a bar magnet is (JT-1)
At a given place on the Earth’s surface, the horizontal component of Earth’s magnetic field is 9 × 10-5 T and the resultant magnetic field is 180 × 10-6. Calculate the angle of dip at this place.- a)45o
- b)0o
- c)60o
- d)30o
Correct answer is option 'C'. Can you explain this answer?
At a given place on the Earth’s surface, the horizontal component of Earth’s magnetic field is 9 × 10-5 T and the resultant magnetic field is 180 × 10-6. Calculate the angle of dip at this place.
a)
45o
b)
0o
c)
60o
d)
30o
|
|
Hansa Sharma answered |
Given: H = 9 × 10-5; R = 180 × 10-6 = 18 × 10-5
The required equation ➔ H=Rcosδ
Therefore, δ = cos-1 1/2
The required equation ➔ H=Rcosδ
Therefore, δ = cos-1 1/2
=60o
Thus, the angle of dip is 60o.
Thus, the angle of dip is 60o.
In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26G and the dip angle is 600. What is the magnetic field of the earth at this location- a)0.65G
- b)0.62G
- c)0.58G
- d)0.52G
Correct answer is option 'D'. Can you explain this answer?
In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26G and the dip angle is 600. What is the magnetic field of the earth at this location
a)
0.65G
b)
0.62G
c)
0.58G
d)
0.52G
|
Om Desai answered |
The earth's magnetic field is Be and its horizontal and vertical components are He and Hv
cosθ= He/Be
∴cos60o= (0.26×10−4/ Be )T
⇒Be=(0.26×10−4)/ (½)=0.52×10−4T=0.52G
cosθ= He/Be
∴cos60o= (0.26×10−4/ Be )T
⇒Be=(0.26×10−4)/ (½)=0.52×10−4T=0.52G
A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 12 A ?- a)4.48 T
- b)5.48 T
- c)44.8 T
- d)48 T
Correct answer is option 'A'. Can you explain this answer?
A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 12 A ?
a)
4.48 T
b)
5.48 T
c)
44.8 T
d)
48 T
|
Sankar Singh answered |
Calculation of Magnetic Field B in the Core
Given:
Mean radius of Rowland ring, r = 15 cm = 0.15 m
Number of turns of wire, N = 3500
Relative permeability of ferromagnetic core, μr = 800
Magnetising current, I = 12 A
The magnetic field B in the core of Rowland ring can be calculated using the formula:
B = (μ0 * N * I) / (2 * r)
where, μ0 is the permeability of free space
μ0 = 4π * 10^-7 Tm/A
Substituting the given values in the formula,
B = (4π * 10^-7 Tm/A * 3500 * 12 A) / (2 * 0.15 m)
B = 4.48 T
Therefore, the magnetic field B in the core of Rowland ring for a magnetising current of 12 A is 4.48 T, which is option A.
Given:
Mean radius of Rowland ring, r = 15 cm = 0.15 m
Number of turns of wire, N = 3500
Relative permeability of ferromagnetic core, μr = 800
Magnetising current, I = 12 A
The magnetic field B in the core of Rowland ring can be calculated using the formula:
B = (μ0 * N * I) / (2 * r)
where, μ0 is the permeability of free space
μ0 = 4π * 10^-7 Tm/A
Substituting the given values in the formula,
B = (4π * 10^-7 Tm/A * 3500 * 12 A) / (2 * 0.15 m)
B = 4.48 T
Therefore, the magnetic field B in the core of Rowland ring for a magnetising current of 12 A is 4.48 T, which is option A.
When is the angle of dip at a place equal to 45o?- a)When the vertical and horizontal components of earth’s magnetic field are equal
- b)When the vertical component is twice the horizontal component of earth’s magnetic field
- c)When the vertical component is half the horizontal component of earth’s magnetic field
- d)When either the vertical component or the horizontal components of earth’s magnetic field is equal to zero
Correct answer is option 'A'. Can you explain this answer?
When is the angle of dip at a place equal to 45o?
a)
When the vertical and horizontal components of earth’s magnetic field are equal
b)
When the vertical component is twice the horizontal component of earth’s magnetic field
c)
When the vertical component is half the horizontal component of earth’s magnetic field
d)
When either the vertical component or the horizontal components of earth’s magnetic field is equal to zero
|
Sushil Kumar answered |
Yes, the angle of dip at a place is equal to 45o, when the vertical and horizontal components of earth’s magnetic field are equal. In this case ➔ δ=45o
So, BV=BH.
So, BV=BH.
A cube-shaped permanent magnet is made of a ferromagnetic material with a magnetization M of about The side length is 2 cm. Magnetic dipole moment of the magnet is.
- a)5Am2
- b)3Am2
- c)4Am2
- d)6Am2
Correct answer is option 'C'. Can you explain this answer?
A cube-shaped permanent magnet is made of a ferromagnetic material with a magnetization M of about The side length is 2 cm. Magnetic dipole moment of the magnet is.
a)
5Am2
b)
3Am2
c)
4Am2
d)
6Am2
|
|
Nikita Singh answered |
Correct Answer :- C
Explanation : Magnetic Moment = Magnetization × Volume
Side of cube = 20 cm
= 0.2 m
= 500 × 0.2 × 0.2 × 0.2
= 4Am2
Correct unit of Bohr magneton is- a)T
- b)T/J
- c)J/T
- d)J
Correct answer is option 'C'. Can you explain this answer?
Correct unit of Bohr magneton is
a)
T
b)
T/J
c)
J/T
d)
J
|
|
Sushil Kumar answered |
The Bohr magneton μB is a physical constant and the natural unit for expressing the magnetic moment of an electron caused by either its orbital or spin angular momentum.
μB= eℏ/2me
where e is the elementary charge, ℏ is the reduced Planck's constant, me is the electron rest mass.
The value of Bohr magneton in SI units is 9.27400968(20)×10−24JT−1
μB= eℏ/2me
where e is the elementary charge, ℏ is the reduced Planck's constant, me is the electron rest mass.
The value of Bohr magneton in SI units is 9.27400968(20)×10−24JT−1
What is the unit of susceptibility?- a)Am-1
- b)Am2
- c)No units
- d)Am
Correct answer is option 'C'. Can you explain this answer?
What is the unit of susceptibility?
a)
Am-1
b)
Am2
c)
No units
d)
Am
|
|
Hansa Sharma answered |
In electromagnetism the magnetic susceptibility (Latin: susceptibilis, “receptive”; denoted X) is a measure of how much a material will become magnetized in an applied magnetic field. Mathematically, it is the ratio of magnetization M(magnetic moment per unit volume) to the applied magnetizing field intensity H.
A short bar magnet of magnetic moment 5.25×10−2JT−1 is placed with its axis perpendicular to the earth’s field direction. At what distance from the centre of the magnet, the resultant field is inclined at 45 with earth’s field on its normal bisector . Magnitude of the earth’s field at the place is given to be 0.42 G. Ignore the length of the magnet in comparison to the distances involved.- a)5.5 cm
- b)7.0 cm
- c)6.0 cm
- d)5 cm
Correct answer is option 'D'. Can you explain this answer?
A short bar magnet of magnetic moment 5.25×10−2JT−1 is placed with its axis perpendicular to the earth’s field direction. At what distance from the centre of the magnet, the resultant field is inclined at 45 with earth’s field on its normal bisector . Magnitude of the earth’s field at the place is given to be 0.42 G. Ignore the length of the magnet in comparison to the distances involved.
a)
5.5 cm
b)
7.0 cm
c)
6.0 cm
d)
5 cm
|
|
Nandini Iyer answered |
According to the question, the resultant field is inclined at 45o with earth's magnetic field.
tanθ=BH/B
θ=45o
tanθ=1=BH/B
BH=B= μoM/4πr3
Given, B= 0.42×10−4T
M=5.25×10−2J/T
Therefore,0.42+10−4=10−7×[(5.25×10−2)/r3]
r3=12.5×10−5=125×10−6
r=5×10−2m = 5 cm
tanθ=BH/B
θ=45o
tanθ=1=BH/B
BH=B= μoM/4πr3
Given, B= 0.42×10−4T
M=5.25×10−2J/T
Therefore,0.42+10−4=10−7×[(5.25×10−2)/r3]
r3=12.5×10−5=125×10−6
r=5×10−2m = 5 cm
A cube-shaped permanent magnet is made of a ferromagnetic material with a magnetization M of about The side length is 2 cm. Magnetic field due to the magnet at a point 10 cm from the magnet along its axis is
- a)0.003 T
- b)0.002 T
- c)0.004 T
- d)0.001 T
Correct answer is option 'D'. Can you explain this answer?
A cube-shaped permanent magnet is made of a ferromagnetic material with a magnetization M of about The side length is 2 cm. Magnetic field due to the magnet at a point 10 cm from the magnet along its axis is
a)
0.003 T
b)
0.002 T
c)
0.004 T
d)
0.001 T
|
|
Riya Banerjee answered |
Correct Answer :- d
Explanation : μtotal = MV
= (8*105)(2*10-2)
= 6A m2
Magnetic field on the axis of a current loop with magnetic material μtotal is:
B = μ0 μtotal / (2π(x2 + a2)1/2
B = (4π*10-7)(6) / [2π(0.1)]
= 1 * 10-3 T
= 0.001 T
Declination is the angle between:- a)horizontal and vertical components of earth’s magnetic field
- b)horizontal component and total magnetic field of the earth
- c)geographic and magnetic meridian
- d)geographic meridian and horizontal component of earth’s magnetic field
Correct answer is option 'C'. Can you explain this answer?
Declination is the angle between:
a)
horizontal and vertical components of earth’s magnetic field
b)
horizontal component and total magnetic field of the earth
c)
geographic and magnetic meridian
d)
geographic meridian and horizontal component of earth’s magnetic field
|
|
Pooja Mehta answered |
Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north (the direction the north end of a compass needle points, corresponding to the direction of the Earth's magnetic field lines) and true north (the direction along a meridian towards the geographic North Pole).
For diamagnetic materials- a)additional field caused by atoms is always parallel in direction to that of the external field
- b)additional field caused by atoms is always perpendicular in direction to that of the external field
- c)additional field caused by atoms is always in same direction as that of the external field
- d)additional field caused by atoms is always opposite in direction to that of the external field
Correct answer is option 'D'. Can you explain this answer?
For diamagnetic materials
a)
additional field caused by atoms is always parallel in direction to that of the external field
b)
additional field caused by atoms is always perpendicular in direction to that of the external field
c)
additional field caused by atoms is always in same direction as that of the external field
d)
additional field caused by atoms is always opposite in direction to that of the external field
|
|
Nikita Singh answered |
It is because when we make a group of electrons inside the material it is called domain. So when we apply an external magnetic field on the material. Those domains start to align themselves in the direction of the magnetic field. BUT NOT ALL DOMAINS ALIGN THEMSELVES IN THAT DIRECTION. So option D is correct.
If a magnet is suspended over a container of liquid air, it attracts droplets to its poles. The droplets contain only liquid oxygen and no nitrogen because- a)oxygen is ferromagnetic whereas nitrogen is diamagnetic
- b)oxygen is ferrimagnetic whereas nitrogen is diamagnetic
- c)oxygen is diamagnetic whereas nitrogen is paramagnetic
- d)oxygen is paramagnetic whereas nitrogen is diamagnetic
Correct answer is option 'D'. Can you explain this answer?
If a magnet is suspended over a container of liquid air, it attracts droplets to its poles. The droplets contain only liquid oxygen and no nitrogen because
a)
oxygen is ferromagnetic whereas nitrogen is diamagnetic
b)
oxygen is ferrimagnetic whereas nitrogen is diamagnetic
c)
oxygen is diamagnetic whereas nitrogen is paramagnetic
d)
oxygen is paramagnetic whereas nitrogen is diamagnetic
|
|
Anaya Patel answered |
If a magnet is suspended over a container of liquid air, it attracts droplets to its poles. The droplets contain only liquid oxygen; even though nitrogen is the primary constituent of air, it is not attracted to the magnet. Explain what this tells you about the magnetic susceptibilities of oxygen and nitrogen, and explain why a magnet in ordinary, room-temperature air doesn’t attract molecules of oxygen gas to its poles.
Which one of the Maxwell’s laws leads to the conclusion that there are no magnetic field loops that are not closed?- a)Faraday’s law
- b)Gauss’ law for magnetism
- c)Gauss’ law for electricity
- d)Ampere-Maxwell law
Correct answer is option 'B'. Can you explain this answer?
Which one of the Maxwell’s laws leads to the conclusion that there are no magnetic field loops that are not closed?
a)
Faraday’s law
b)
Gauss’ law for magnetism
c)
Gauss’ law for electricity
d)
Ampere-Maxwell law
|
Jyoti Kapoor answered |
In physics, Gauss's law for magnetism is one of the four Maxwell's equations that underlie classical electrodynamics. It states that the magnetic field B has divergence equal to zero,in other words, that it is a solenoidal vector field. It is equivalent to the statement that magnetic monopoles do not exist.Rather than "magnetic charges", the basic entity for magnetism is the magnetic dipole. (If monopoles were ever found, the law would have to be modified, as elaborated below.)
Gauss's law for magnetism can be written in two forms, a differential form and an integral form. These forms are equivalent due to the divergence theorem.
The name "Gauss's law for magnetism"is not universally used. The law is also called "Absence of free magnetic poles";one reference even explicitly says the law has "no name".It is also referred to as the "transversality requirement"because for plane waves it requires that the polarization be transverse to the direction of propagation.
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.Assertion : Electromagnetic are made of soft iron.Reason : Coercivity of soft iron is small.- a)If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
- b)If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
- c)If the Assertion is correct but Reason is incorrect.
- d)If both the Assertion and Reason are incorrect.
Correct answer is option 'B'. Can you explain this answer?
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
Assertion : Electromagnetic are made of soft iron.
Reason : Coercivity of soft iron is small.
a)
If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
b)
If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
c)
If the Assertion is correct but Reason is incorrect.
d)
If both the Assertion and Reason are incorrect.
|
|
Priyanka Sharma answered |
Electromagnets are magnets, which can be turned on and off by switching the current on and off. As the material in electromagnets is subjected to cyclic changes (magnification and demagnetisation), the hysteresis loss of the material must be small. The material should attain high value of I and B with low value of magnetising field intensity H. As soft iron has small coercivity, so it is a best choice for this purpose.
Identify the expression for horizontal component from the following.- a)BH=Bcosδ
- b)B=BH cosδ
- c)
- d)BH=2Bcosδ
Correct answer is option 'A'. Can you explain this answer?
Identify the expression for horizontal component from the following.
a)
BH=Bcosδ
b)
B=BH cosδ
c)
d)
BH=2Bcosδ
|
|
Preeti Iyer answered |
Horizontal component is a component of Earth’s magnetic field along the horizontal direction in the magnetic meridian. It is denoted by BH. If B is the intensity of Earth’s total magnetic field, then the horizontal component of Earth’s magnetic field is given by:
BH=Bcosδ
BH=Bcosδ
For paramagnetic materials- a)orbital and spin magnetic moments of the electrons are of the order of bohr magneton
- b)orbital magnetic moments of the electrons are zero
- c)orbital and spin magnetic moments of the electrons are less than zero
- d)spin magnetic moments of the electrons are zero
Correct answer is option 'A'. Can you explain this answer?
For paramagnetic materials
a)
orbital and spin magnetic moments of the electrons are of the order of bohr magneton
b)
orbital magnetic moments of the electrons are zero
c)
orbital and spin magnetic moments of the electrons are less than zero
d)
spin magnetic moments of the electrons are zero
|
|
Shubham Jain answered |
Paramagnetic materials are those materials that are weakly attracted by a magnetic field. They have unpaired electrons in their outermost shell, which causes a net magnetic moment due to the spin and orbital motion of the electrons.
Orbital and Spin Magnetic Moments:
- Orbital magnetic moment: It is the magnetic moment of an electron due to its motion around the nucleus.
- Spin magnetic moment: It is the magnetic moment of an electron due to its intrinsic spin.
Order of Bohr Magneton:
- Bohr magneton is a unit of magnetic moment, which is equal to approximately 9.27 x 10^-24 joules per tesla.
- The orbital and spin magnetic moments of electrons in paramagnetic materials are of the order of Bohr magneton.
Explanation of Option A:
- Option A states that the orbital and spin magnetic moments of electrons in paramagnetic materials are of the order of Bohr magneton.
- This is correct because the unpaired electrons in paramagnetic materials have a net magnetic moment due to their spin and orbital motion, which is of the order of Bohr magneton.
- This magnetic moment causes the paramagnetic material to be weakly attracted to a magnetic field.
Other Options:
- Option B states that the orbital magnetic moments of electrons in paramagnetic materials are zero, which is incorrect because the unpaired electrons have an orbital magnetic moment.
- Option C states that the orbital and spin magnetic moments of electrons in paramagnetic materials are less than zero, which is incorrect because magnetic moments cannot be negative.
- Option D states that the spin magnetic moments of electrons in paramagnetic materials are zero, which is incorrect because the unpaired electrons have a spin magnetic moment.
Orbital and Spin Magnetic Moments:
- Orbital magnetic moment: It is the magnetic moment of an electron due to its motion around the nucleus.
- Spin magnetic moment: It is the magnetic moment of an electron due to its intrinsic spin.
Order of Bohr Magneton:
- Bohr magneton is a unit of magnetic moment, which is equal to approximately 9.27 x 10^-24 joules per tesla.
- The orbital and spin magnetic moments of electrons in paramagnetic materials are of the order of Bohr magneton.
Explanation of Option A:
- Option A states that the orbital and spin magnetic moments of electrons in paramagnetic materials are of the order of Bohr magneton.
- This is correct because the unpaired electrons in paramagnetic materials have a net magnetic moment due to their spin and orbital motion, which is of the order of Bohr magneton.
- This magnetic moment causes the paramagnetic material to be weakly attracted to a magnetic field.
Other Options:
- Option B states that the orbital magnetic moments of electrons in paramagnetic materials are zero, which is incorrect because the unpaired electrons have an orbital magnetic moment.
- Option C states that the orbital and spin magnetic moments of electrons in paramagnetic materials are less than zero, which is incorrect because magnetic moments cannot be negative.
- Option D states that the spin magnetic moments of electrons in paramagnetic materials are zero, which is incorrect because the unpaired electrons have a spin magnetic moment.
A toroidal solenoid with 500 turns is wound on a ring with a mean radius of 2.90 cm. Find the current in the winding that is required to set up a magnetic field of 0.350 T in the ring if the ring is made of annealed iron Km=1400- a)82.5mA
- b)72.5mA
- c)79.5mA
- d)69.5mA
Correct answer is option 'B'. Can you explain this answer?
A toroidal solenoid with 500 turns is wound on a ring with a mean radius of 2.90 cm. Find the current in the winding that is required to set up a magnetic field of 0.350 T in the ring if the ring is made of annealed iron Km=1400
a)
82.5mA
b)
72.5mA
c)
79.5mA
d)
69.5mA
|
Geetika Shah answered |
Given,
Number of turns, N = 500 turns
Radius of solenoid, r = 2.9
Relative permeability of annealed iron of Km=1400
Permeability of free space, μ0 =4π
The magnetic field, B=0.350 T
Therefore,
μ/μ0= μr
μ= μr x μ0
B= μrμ0NI/2πR
0.350=1400x4x 3.14x500xI/2xπx2.90
I=72.mA
Number of turns, N = 500 turns
Radius of solenoid, r = 2.9
Relative permeability of annealed iron of Km=1400
Permeability of free space, μ0 =4π
The magnetic field, B=0.350 T
Therefore,
μ/μ0= μr
μ= μr x μ0
B= μrμ0NI/2πR
0.350=1400x4x 3.14x500xI/2xπx2.90
I=72.mA
A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at 14 cm from the centre of the magnet. The earth’s magnetic field at the place is 0.36 G and the angle of dip is zero. What is the total magnetic field on the normal bisector of the magnet at the same distance as the null–point (i.e., 14 cm) from the centre of the magnet? (At null points, field due to a magnet is equal and opposite to the horizontal component of earth’s magnetic field.)- a)0.64 G in the direction of earth’s field.
- b)0.62 G in the direction of earth’s field.
- c)0.54 G in the direction of earth’s field.
- d)0.58 G in the direction of earth’s field.
Correct answer is option 'C'. Can you explain this answer?
A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at 14 cm from the centre of the magnet. The earth’s magnetic field at the place is 0.36 G and the angle of dip is zero. What is the total magnetic field on the normal bisector of the magnet at the same distance as the null–point (i.e., 14 cm) from the centre of the magnet? (At null points, field due to a magnet is equal and opposite to the horizontal component of earth’s magnetic field.)
a)
0.64 G in the direction of earth’s field.
b)
0.62 G in the direction of earth’s field.
c)
0.54 G in the direction of earth’s field.
d)
0.58 G in the direction of earth’s field.
|
Janhavi Kaur answered |
To find the total magnetic field on the normal bisector of the magnet at the same distance as the null point, we need to consider the contributions from both the magnet and the Earth's magnetic field.
1. Magnetic Field due to the Magnet:
The null points on the axis of the magnet indicate that the field due to the magnet is equal and opposite to the horizontal component of the Earth's magnetic field. Therefore, the horizontal component of the magnet's field at the null point is equal to the Earth's magnetic field.
Given that the null point is at a distance of 14 cm from the center of the magnet, we can use the formula for the magnetic field along the axis of a short bar magnet:
B = (μ₀/4π) * (2M/(d³))
Where:
B is the magnetic field
μ₀ is the permeability of free space (4π x 10^-7 Tm/A)
M is the magnetic moment of the magnet
d is the distance from the center of the magnet
Since the null point is at 14 cm from the center, the distance from the center to the null point is 7 cm (0.07 m). The magnetic field due to the magnet at this point is equal to the Earth's magnetic field, which is given as 0.36 G (1 G = 10^-4 T).
2. Total Magnetic Field:
The total magnetic field on the normal bisector at the same distance from the center of the magnet can be found by vector addition of the Earth's magnetic field and the magnetic field due to the magnet.
Since the angle of dip is zero, the Earth's magnetic field is entirely horizontal. Therefore, the total magnetic field will be the vector sum of the Earth's magnetic field and the magnetic field due to the magnet.
The total magnetic field is given by:
B_total = √(B_magnet² + B_earth² + 2B_magnetB_earthcosθ)
Where:
B_magnet is the magnetic field due to the magnet
B_earth is the Earth's magnetic field
θ is the angle between the two fields (which is 180° since they are opposite in direction)
Plugging in the values:
B_total = √((0.36 G)² + (0.36 G)² + 2(0.36 G)(0.36 G)cos180°)
B_total = √(0.1296 G² + 0.1296 G² - 2(0.1296 G²))
B_total = √(0.2592 G² - 0.2592 G²)
B_total = √0 G²
B_total = 0 G
Therefore, the total magnetic field on the normal bisector of the magnet at the same distance as the null point is 0 G. None of the given options (a, b, c, d) match the correct answer.
1. Magnetic Field due to the Magnet:
The null points on the axis of the magnet indicate that the field due to the magnet is equal and opposite to the horizontal component of the Earth's magnetic field. Therefore, the horizontal component of the magnet's field at the null point is equal to the Earth's magnetic field.
Given that the null point is at a distance of 14 cm from the center of the magnet, we can use the formula for the magnetic field along the axis of a short bar magnet:
B = (μ₀/4π) * (2M/(d³))
Where:
B is the magnetic field
μ₀ is the permeability of free space (4π x 10^-7 Tm/A)
M is the magnetic moment of the magnet
d is the distance from the center of the magnet
Since the null point is at 14 cm from the center, the distance from the center to the null point is 7 cm (0.07 m). The magnetic field due to the magnet at this point is equal to the Earth's magnetic field, which is given as 0.36 G (1 G = 10^-4 T).
2. Total Magnetic Field:
The total magnetic field on the normal bisector at the same distance from the center of the magnet can be found by vector addition of the Earth's magnetic field and the magnetic field due to the magnet.
Since the angle of dip is zero, the Earth's magnetic field is entirely horizontal. Therefore, the total magnetic field will be the vector sum of the Earth's magnetic field and the magnetic field due to the magnet.
The total magnetic field is given by:
B_total = √(B_magnet² + B_earth² + 2B_magnetB_earthcosθ)
Where:
B_magnet is the magnetic field due to the magnet
B_earth is the Earth's magnetic field
θ is the angle between the two fields (which is 180° since they are opposite in direction)
Plugging in the values:
B_total = √((0.36 G)² + (0.36 G)² + 2(0.36 G)(0.36 G)cos180°)
B_total = √(0.1296 G² + 0.1296 G² - 2(0.1296 G²))
B_total = √(0.2592 G² - 0.2592 G²)
B_total = √0 G²
B_total = 0 G
Therefore, the total magnetic field on the normal bisector of the magnet at the same distance as the null point is 0 G. None of the given options (a, b, c, d) match the correct answer.
How can a magnetic field be produced?- a)Using a permanent magnet
- b)Electric current
- c)Using a temporary magnet
- d)Using a permanent magnet or electric current
Correct answer is option 'D'. Can you explain this answer?
How can a magnetic field be produced?
a)
Using a permanent magnet
b)
Electric current
c)
Using a temporary magnet
d)
Using a permanent magnet or electric current
|
Sanaya Kumar answered |
Production of Magnetic Field
Magnetic field can be produced in various ways. The correct answer is option 'D', which states that a magnetic field can be produced using a permanent magnet or electric current. Let's discuss both of these methods in detail.
Using a Permanent Magnet
A permanent magnet is a magnet that retains its magnetic properties even in the absence of an external magnetic field. The magnetic field produced by a permanent magnet is due to the alignment of its atomic dipoles. The magnetic field produced by a permanent magnet is static and does not change in strength or direction over time.
Using an Electric Current
An electric current is a flow of electric charge through a conductor. When an electric current flows through a conductor, it produces a magnetic field around the conductor. The strength and direction of the magnetic field depend on the strength and direction of the current flowing through the conductor. The magnetic field produced by an electric current is dynamic and can change in strength and direction over time.
Conclusion
In conclusion, a magnetic field can be produced using a permanent magnet or electric current. While the magnetic field produced by a permanent magnet is static, the magnetic field produced by an electric current is dynamic and can change in strength and direction over time.
Magnetic field can be produced in various ways. The correct answer is option 'D', which states that a magnetic field can be produced using a permanent magnet or electric current. Let's discuss both of these methods in detail.
Using a Permanent Magnet
A permanent magnet is a magnet that retains its magnetic properties even in the absence of an external magnetic field. The magnetic field produced by a permanent magnet is due to the alignment of its atomic dipoles. The magnetic field produced by a permanent magnet is static and does not change in strength or direction over time.
Using an Electric Current
An electric current is a flow of electric charge through a conductor. When an electric current flows through a conductor, it produces a magnetic field around the conductor. The strength and direction of the magnetic field depend on the strength and direction of the current flowing through the conductor. The magnetic field produced by an electric current is dynamic and can change in strength and direction over time.
Conclusion
In conclusion, a magnetic field can be produced using a permanent magnet or electric current. While the magnetic field produced by a permanent magnet is static, the magnetic field produced by an electric current is dynamic and can change in strength and direction over time.
The angle of dip at a certain place on Earth is 30o and the magnitude of Earth’s horizontal component of magnetic field is 0.35 G. Find the magnetic field at that place on Earth.- a)0.35 G
- b)0.40 G
- c)0.45 G
- d)0.50 G
Correct answer is option 'B'. Can you explain this answer?
The angle of dip at a certain place on Earth is 30o and the magnitude of Earth’s horizontal component of magnetic field is 0.35 G. Find the magnetic field at that place on Earth.
a)
0.35 G
b)
0.40 G
c)
0.45 G
d)
0.50 G
|
|
Lavanya Menon answered |
Given: Horizontal component (H) = 0.35 G; Angle of dip (δ) = 30o
Required equation ➔ cosδ= H/B
Therefore, the magnitude of the magnetic field at that place is 0.40 G.
Required equation ➔ cosδ= H/B
Therefore, the magnitude of the magnetic field at that place is 0.40 G.
Magnetic field strength due to a short bar magnet on its axial line at a distance x is B. What is its value at the same distance on the equatorial line?- a)B/2
- b)B
- c)2B
- d)4B
Correct answer is option 'A'. Can you explain this answer?
Magnetic field strength due to a short bar magnet on its axial line at a distance x is B. What is its value at the same distance on the equatorial line?
a)
B/2
b)
B
c)
2B
d)
4B
|
Vivek Rana answered |
The magnetic field at any axial point is given by, B = 2μo/ 4πx3
Similarly, the field at any equatorial point is given by, B = μo/ 4πx3
Thus, the field at any equatorial point is half of what it is at an axial point.
Similarly, the field at any equatorial point is given by, B = μo/ 4πx3
Thus, the field at any equatorial point is half of what it is at an axial point.
Which of the following statements about magnetic field lines true?- a)The magnetic field lines of a magnet (or a solenoid) form continuous closed loops
- b)The smaller the number of field lines crossing per unit area, the stronger is the magnitude of the magnetic field B.
- c)The perpendicular to the field line at a given point gives direction of magnetic field
- d)The larger the number of field lines crossing per unit area, the weaker is the magnitude of the magnetic field B.
Correct answer is option 'A'. Can you explain this answer?
Which of the following statements about magnetic field lines true?
a)
The magnetic field lines of a magnet (or a solenoid) form continuous closed loops
b)
The smaller the number of field lines crossing per unit area, the stronger is the magnitude of the magnetic field B.
c)
The perpendicular to the field line at a given point gives direction of magnetic field
d)
The larger the number of field lines crossing per unit area, the weaker is the magnitude of the magnetic field B.
|
Krishna Iyer answered |
Magnetic poles exist in pairs. It is not possible to isolate a north pole or a south pole. Magnetic field lines start from the north pole and go to the south pole and return to the north pole. They form continuous closed loops unlike electric lines of force which do not as an electric monopole, a single charge does exist.
A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at 220 with the horizontal. The horizontal component of the earth’s magnetic field at the place is known to be 0.35 G. Determine the magnitude of the earth’s magnetic field at the place.- a)0.48G
- b)0.28G
- c)0.58G
- d)0.38G
Correct answer is option 'D'. Can you explain this answer?
A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at 220 with the horizontal. The horizontal component of the earth’s magnetic field at the place is known to be 0.35 G. Determine the magnitude of the earth’s magnetic field at the place.
a)
0.48G
b)
0.28G
c)
0.58G
d)
0.38G
|
|
Hansa Sharma answered |
We know the horizontal component of earth magnetic field H=R cos θ
Where θ=angle of dip=220 and the value of H=0.35G
So, putting the values respectively R= H/cosθ=0.35/cos22=0.35/0.927=0.377=0.38G
Where θ=angle of dip=220 and the value of H=0.35G
So, putting the values respectively R= H/cosθ=0.35/cos22=0.35/0.927=0.377=0.38G
In which case of comparing solenoid and bar magnet there is no exact similarity?- a)There is a current entering and a current leaving a solenoid
- b)soenoid can be broken into two weaker solenoids
- c)flux lines enter one end of a solenoid
- d)moving a small compass needle in the neighbourhood of a solenoid enables tracing the flux lines
Correct answer is option 'A'. Can you explain this answer?
In which case of comparing solenoid and bar magnet there is no exact similarity?
a)
There is a current entering and a current leaving a solenoid
b)
soenoid can be broken into two weaker solenoids
c)
flux lines enter one end of a solenoid
d)
moving a small compass needle in the neighbourhood of a solenoid enables tracing the flux lines
|
|
Kiran Khanna answered |
Comparing Solenoid and Bar Magnet
Introduction:
Solenoid and bar magnet are two types of magnets that have different properties. However, there are some similarities between them. In this question, we need to identify the case where there is no exact similarity between solenoid and bar magnet.
Answer:
The correct answer is option 'A' - "There is a current entering and a current leaving a solenoid". Let's understand why this is the correct answer.
Solenoid:
A solenoid is a coil of wire that produces a magnetic field when an electric current is passed through it. The magnetic field produced by a solenoid is similar to that of a bar magnet. However, there are some differences.
Bar Magnet:
A bar magnet is a permanent magnet that has a north pole and a south pole. The magnetic field of a bar magnet is uniform and is strongest at the poles.
Comparison:
Now let's compare the two magnets based on the given options.
a) There is a current entering and a current leaving a solenoid:
This is a property unique to solenoids. When an electric current is passed through a solenoid, there is a current entering at one end and a current leaving at the other end. This is because a solenoid is a coil of wire that is wrapped around a core. As a result, the magnetic field produced by a solenoid is concentrated inside the coil and is weaker outside.
b) Solenoid can be broken into two weaker solenoids:
This is a property that is similar to a bar magnet. A bar magnet can be broken into two weaker magnets, each with its own north and south pole. Similarly, a solenoid can be broken into two weaker solenoids, each with its own magnetic field.
c) Flux lines enter one end of a solenoid:
This is a property that is similar to a bar magnet. The magnetic field of a bar magnet is uniform and the flux lines enter at one end and exit at the other end. Similarly, the magnetic field of a solenoid is strongest at the ends and the flux lines enter at one end and exit at the other end.
d) Moving a small compass needle in the neighbourhood of a solenoid enables tracing the flux lines:
This is a property that is similar to a bar magnet. The magnetic field of a bar magnet can be visualized using iron filings or a small compass needle. Similarly, the magnetic field of a solenoid can be visualized using a small compass needle.
Conclusion:
Based on the above comparison, we can see that option 'A' is the correct answer as it is the only option that is unique to solenoids and does not have a similar property in bar magnets.
Introduction:
Solenoid and bar magnet are two types of magnets that have different properties. However, there are some similarities between them. In this question, we need to identify the case where there is no exact similarity between solenoid and bar magnet.
Answer:
The correct answer is option 'A' - "There is a current entering and a current leaving a solenoid". Let's understand why this is the correct answer.
Solenoid:
A solenoid is a coil of wire that produces a magnetic field when an electric current is passed through it. The magnetic field produced by a solenoid is similar to that of a bar magnet. However, there are some differences.
Bar Magnet:
A bar magnet is a permanent magnet that has a north pole and a south pole. The magnetic field of a bar magnet is uniform and is strongest at the poles.
Comparison:
Now let's compare the two magnets based on the given options.
a) There is a current entering and a current leaving a solenoid:
This is a property unique to solenoids. When an electric current is passed through a solenoid, there is a current entering at one end and a current leaving at the other end. This is because a solenoid is a coil of wire that is wrapped around a core. As a result, the magnetic field produced by a solenoid is concentrated inside the coil and is weaker outside.
b) Solenoid can be broken into two weaker solenoids:
This is a property that is similar to a bar magnet. A bar magnet can be broken into two weaker magnets, each with its own north and south pole. Similarly, a solenoid can be broken into two weaker solenoids, each with its own magnetic field.
c) Flux lines enter one end of a solenoid:
This is a property that is similar to a bar magnet. The magnetic field of a bar magnet is uniform and the flux lines enter at one end and exit at the other end. Similarly, the magnetic field of a solenoid is strongest at the ends and the flux lines enter at one end and exit at the other end.
d) Moving a small compass needle in the neighbourhood of a solenoid enables tracing the flux lines:
This is a property that is similar to a bar magnet. The magnetic field of a bar magnet can be visualized using iron filings or a small compass needle. Similarly, the magnetic field of a solenoid can be visualized using a small compass needle.
Conclusion:
Based on the above comparison, we can see that option 'A' is the correct answer as it is the only option that is unique to solenoids and does not have a similar property in bar magnets.
The ferromagnetic materials can be magnetised easily because- a)Ferromagnetic materials have low susceptibility and permeability
- b)Ferromagnetic materials have high susceptibility and low permeability
- c)Ferromagnetic materials have high susceptibility and permeability
- d)Ferromagnetic materials have low susceptibility and high permeability
Correct answer is option 'C'. Can you explain this answer?
The ferromagnetic materials can be magnetised easily because
a)
Ferromagnetic materials have low susceptibility and permeability
b)
Ferromagnetic materials have high susceptibility and low permeability
c)
Ferromagnetic materials have high susceptibility and permeability
d)
Ferromagnetic materials have low susceptibility and high permeability
|
Rounak Goyal answered |
Such materials are called ferromagnetic, after the Latin word for iron, ferrum. Not only do ferromagnetic materials respond strongly to magnets (the way iron is attracted to magnets), they can also be magnetized themselves—that is, they can be induced to be magnetic or made into permanent magnets.
Which one of the following is feebly repelled by a magnet?- a)Diamagnetic materials
- b)Paramagnetic materials
- c)Ferromagnetic materials
- d)Ferrimagetic materials
Correct answer is option 'A'. Can you explain this answer?
Which one of the following is feebly repelled by a magnet?
a)
Diamagnetic materials
b)
Paramagnetic materials
c)
Ferromagnetic materials
d)
Ferrimagetic materials
|
Pragati Dey answered |
Diamagnetic materials are feebly repelled by a magnet. Diamagnetism is a property exhibited by certain materials that causes them to create a weak magnetic field in opposition to an externally applied magnetic field. This effect is very weak and is easily overcome by stronger magnetic fields.
Diamagnetic materials have all of their electrons paired up in their atomic or molecular orbitals, resulting in a net magnetic moment of zero. When a diamagnetic material is exposed to a magnetic field, the electrons in the material slightly rearrange themselves to create a magnetic field in the opposite direction. This opposing magnetic field causes the material to be repelled by the magnet.
Some examples of diamagnetic materials include bismuth, copper, gold, and water. These materials have a weak response to a magnetic field and are often referred to as non-magnetic materials.
Diamagnetism is a fundamental property of matter and is present in all materials to some degree. However, its effects are typically very weak and only become noticeable in the presence of strong magnetic fields. In comparison to paramagnetic, ferromagnetic, and ferrimagnetic materials, diamagnetic materials exhibit the weakest response to magnetic fields.
In summary, diamagnetic materials are feebly repelled by a magnet due to their ability to create a weak magnetic field in opposition to an externally applied magnetic field. This diamagnetic response is a result of the arrangement of electrons in these materials and is much weaker than the responses exhibited by paramagnetic, ferromagnetic, and ferrimagnetic materials.
Diamagnetic materials have all of their electrons paired up in their atomic or molecular orbitals, resulting in a net magnetic moment of zero. When a diamagnetic material is exposed to a magnetic field, the electrons in the material slightly rearrange themselves to create a magnetic field in the opposite direction. This opposing magnetic field causes the material to be repelled by the magnet.
Some examples of diamagnetic materials include bismuth, copper, gold, and water. These materials have a weak response to a magnetic field and are often referred to as non-magnetic materials.
Diamagnetism is a fundamental property of matter and is present in all materials to some degree. However, its effects are typically very weak and only become noticeable in the presence of strong magnetic fields. In comparison to paramagnetic, ferromagnetic, and ferrimagnetic materials, diamagnetic materials exhibit the weakest response to magnetic fields.
In summary, diamagnetic materials are feebly repelled by a magnet due to their ability to create a weak magnetic field in opposition to an externally applied magnetic field. This diamagnetic response is a result of the arrangement of electrons in these materials and is much weaker than the responses exhibited by paramagnetic, ferromagnetic, and ferrimagnetic materials.
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
Assertion : A paramagnetic sample display greater magnetisation (for the same magnetic field) when cooled.
Reason : The magnetisation does not depend on temperature.
- a)If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
- b)If both the Assertion and Reason are incorrect.
- c)If the Assertion is correct but Reason is incorrect.
- d)If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
Correct answer is option 'D'. Can you explain this answer?
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
Assertion : A paramagnetic sample display greater magnetisation (for the same magnetic field) when cooled.
Reason : The magnetisation does not depend on temperature.
a)
If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
b)
If both the Assertion and Reason are incorrect.
c)
If the Assertion is correct but Reason is incorrect.
d)
If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
|
|
Ashwin Iyer answered |
Assertion : A paramagnetic sample display greater magnetisation (for the same magnetic field) when cooled.
Reason : The magnetisation does not depend on temperature.
The correct answer to this question is option 'd', which states that both the Assertion and Reason are incorrect. Let's analyze the Assertion and Reason statements individually to understand why this answer is correct.
Assertion: A paramagnetic sample displays greater magnetisation (for the same magnetic field) when cooled.
Reason: The magnetisation does not depend on temperature.
Explanation:
Assertion: A paramagnetic sample displays greater magnetisation (for the same magnetic field) when cooled.
Paramagnetic materials are those materials that have unpaired electrons and are weakly attracted to a magnetic field. When a paramagnetic material is placed in a magnetic field, the external magnetic field aligns the magnetic moments of the unpaired electrons in the material, causing it to become magnetized. This magnetization is directly proportional to the applied magnetic field strength.
The Assertion states that a paramagnetic sample displays greater magnetization when cooled. This statement is incorrect. Cooling a paramagnetic sample does not lead to an increase in its magnetization. The magnetization of a paramagnetic material depends on the strength of the applied magnetic field, not on its temperature. Cooling the sample does not change the number of unpaired electrons or their magnetic moments, which are the factors that determine the magnetization of a paramagnetic material.
Reason: The magnetisation does not depend on temperature.
The Reason states that the magnetization does not depend on temperature. This statement is also incorrect. The magnetization of a paramagnetic material can be affected by temperature. At higher temperatures, thermal energy disrupts the alignment of the magnetic moments, reducing the overall magnetization. As the temperature decreases, the thermal energy decreases, allowing the magnetic moments to align more easily and increasing the magnetization. Therefore, the magnetization of a paramagnetic material can vary with temperature.
In conclusion, both the Assertion and Reason statements are incorrect. The Assertion incorrectly claims that a paramagnetic sample displays greater magnetization when cooled, while the Reason incorrectly states that magnetization does not depend on temperature.
Reason : The magnetisation does not depend on temperature.
The correct answer to this question is option 'd', which states that both the Assertion and Reason are incorrect. Let's analyze the Assertion and Reason statements individually to understand why this answer is correct.
Assertion: A paramagnetic sample displays greater magnetisation (for the same magnetic field) when cooled.
Reason: The magnetisation does not depend on temperature.
Explanation:
Assertion: A paramagnetic sample displays greater magnetisation (for the same magnetic field) when cooled.
Paramagnetic materials are those materials that have unpaired electrons and are weakly attracted to a magnetic field. When a paramagnetic material is placed in a magnetic field, the external magnetic field aligns the magnetic moments of the unpaired electrons in the material, causing it to become magnetized. This magnetization is directly proportional to the applied magnetic field strength.
The Assertion states that a paramagnetic sample displays greater magnetization when cooled. This statement is incorrect. Cooling a paramagnetic sample does not lead to an increase in its magnetization. The magnetization of a paramagnetic material depends on the strength of the applied magnetic field, not on its temperature. Cooling the sample does not change the number of unpaired electrons or their magnetic moments, which are the factors that determine the magnetization of a paramagnetic material.
Reason: The magnetisation does not depend on temperature.
The Reason states that the magnetization does not depend on temperature. This statement is also incorrect. The magnetization of a paramagnetic material can be affected by temperature. At higher temperatures, thermal energy disrupts the alignment of the magnetic moments, reducing the overall magnetization. As the temperature decreases, the thermal energy decreases, allowing the magnetic moments to align more easily and increasing the magnetization. Therefore, the magnetization of a paramagnetic material can vary with temperature.
In conclusion, both the Assertion and Reason statements are incorrect. The Assertion incorrectly claims that a paramagnetic sample displays greater magnetization when cooled, while the Reason incorrectly states that magnetization does not depend on temperature.
Read the following text and answer the following questions on the basis of the same:Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories:(i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI).(ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.To raise the Curie point of rare Earth elements.- a)they are coated with gold.
- b)compounds are formed with transition metals.
- c)they are oxidized
- d)None of the above
Correct answer is option 'B'. Can you explain this answer?
Read the following text and answer the following questions on the basis of the same:
Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories:
(i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI).
(ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.
To raise the Curie point of rare Earth elements.
a)
they are coated with gold.
b)
compounds are formed with transition metals.
c)
they are oxidized
d)
None of the above
|
|
Nabanita Sen answered |
Understanding the Curie Temperature of Rare-Earth Magnets
To comprehend why forming compounds with transition metals raises the Curie temperature of rare-earth elements, it is essential to grasp the concept of magnetism and temperature relationships in materials.
Curie Temperature Explained
- The Curie temperature is the temperature above which a magnet loses its magnetic properties.
- Rare-earth magnets, in their pure form, have Curie temperatures below room temperature, limiting their practical applications.
Role of Transition Metals
- When rare-earth elements such as neodymium or samarium are combined with transition metals like iron, nickel, or cobalt, the resulting compounds exhibit enhanced magnetic properties.
- This combination alters the electronic structure and magnetic interactions within the material, effectively raising the Curie temperature above room temperature.
Advantages of Higher Curie Temperature
- A higher Curie temperature allows these magnets to maintain their magnetism in a wider range of temperatures, making them suitable for various applications, including electronics and aerospace.
- This enables their use in devices that operate in environments where temperature fluctuations occur.
Conclusion
- Thus, the correct answer to how the Curie point of rare-earth elements is raised is option 'B': compounds are formed with transition metals.
- This understanding highlights the importance of material science in enhancing the properties of magnets for advanced technological applications.
To comprehend why forming compounds with transition metals raises the Curie temperature of rare-earth elements, it is essential to grasp the concept of magnetism and temperature relationships in materials.
Curie Temperature Explained
- The Curie temperature is the temperature above which a magnet loses its magnetic properties.
- Rare-earth magnets, in their pure form, have Curie temperatures below room temperature, limiting their practical applications.
Role of Transition Metals
- When rare-earth elements such as neodymium or samarium are combined with transition metals like iron, nickel, or cobalt, the resulting compounds exhibit enhanced magnetic properties.
- This combination alters the electronic structure and magnetic interactions within the material, effectively raising the Curie temperature above room temperature.
Advantages of Higher Curie Temperature
- A higher Curie temperature allows these magnets to maintain their magnetism in a wider range of temperatures, making them suitable for various applications, including electronics and aerospace.
- This enables their use in devices that operate in environments where temperature fluctuations occur.
Conclusion
- Thus, the correct answer to how the Curie point of rare-earth elements is raised is option 'B': compounds are formed with transition metals.
- This understanding highlights the importance of material science in enhancing the properties of magnets for advanced technological applications.
Read the following text and answer the following questions on the basis of the same: Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories: (i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI). (ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.Neodymium permanent magnets lose their magnetism ____ % every 100 years.- a)50
- b)0.5
- c)10
- d)None of the above
Correct answer is option 'B'. Can you explain this answer?
Read the following text and answer the following questions on the basis of the same: Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories: (i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI). (ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.
Neodymium permanent magnets lose their magnetism ____ % every 100 years.
a)
50
b)
0.5
c)
10
d)
None of the above
|
|
Krishna Iyer answered |
Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense. Neodymium magnets may be considered as a permanent magnet.
Read the following text and answer the following questions on the basis of the same:Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories:(i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI).(ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.Neodymium and Samarium are- a)diamagnetic.
- b)paramagnetic.
- c)ferromagnetic.
- d)not magnetic materials.
Correct answer is option 'C'. Can you explain this answer?
Read the following text and answer the following questions on the basis of the same:
Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories:
(i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI).
(ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.
Neodymium and Samarium are
a)
diamagnetic.
b)
paramagnetic.
c)
ferromagnetic.
d)
not magnetic materials.
|
|
Shraddha Chavan answered |
Understanding Neodymium and Samarium Magnets
Neodymium and Samarium-cobalt magnets are classified as ferromagnetic materials. Here's a detailed explanation:
Definition of Ferromagnetism
- Ferromagnetic materials are those that exhibit strong magnetic properties.
- They can be magnetized and retain their magnetism even after the external magnetic field is removed.
Characteristics of Neodymium and Samarium Magnets
- Composition:
- Neodymium magnets are made from an alloy of neodymium, iron, and boron.
- Samarium-cobalt magnets consist of samarium and cobalt.
- Strength:
- Both types are known for their exceptional magnetic strength, much stronger than conventional magnets.
- Neodymium magnets are currently the strongest known permanent magnets.
- Applications:
- Commonly used in various electronic applications, including hard drives, electric motors, and MRI machines.
- Samarium-cobalt magnets are suitable for high-temperature applications, making them ideal for use in space travel and cryogenics.
Curie Temperature and Magnetism
- The Curie temperature indicates the temperature at which a material loses its permanent magnetic properties.
- Though the rare-earth elements have low Curie temperatures in their pure form, their magnetism is significantly enhanced when alloyed with transition metals.
Conclusion
- Because Neodymium and Samarium magnets can be easily magnetized and maintain that magnetism, they are classified as ferromagnetic materials.
- This classification explains their strength and various applications in technology and industry.
In summary, Neodymium and Samarium-cobalt magnets are ferromagnetic due to their ability to be strongly magnetized and retain their magnetism, making them essential in many advanced applications.
Neodymium and Samarium-cobalt magnets are classified as ferromagnetic materials. Here's a detailed explanation:
Definition of Ferromagnetism
- Ferromagnetic materials are those that exhibit strong magnetic properties.
- They can be magnetized and retain their magnetism even after the external magnetic field is removed.
Characteristics of Neodymium and Samarium Magnets
- Composition:
- Neodymium magnets are made from an alloy of neodymium, iron, and boron.
- Samarium-cobalt magnets consist of samarium and cobalt.
- Strength:
- Both types are known for their exceptional magnetic strength, much stronger than conventional magnets.
- Neodymium magnets are currently the strongest known permanent magnets.
- Applications:
- Commonly used in various electronic applications, including hard drives, electric motors, and MRI machines.
- Samarium-cobalt magnets are suitable for high-temperature applications, making them ideal for use in space travel and cryogenics.
Curie Temperature and Magnetism
- The Curie temperature indicates the temperature at which a material loses its permanent magnetic properties.
- Though the rare-earth elements have low Curie temperatures in their pure form, their magnetism is significantly enhanced when alloyed with transition metals.
Conclusion
- Because Neodymium and Samarium magnets can be easily magnetized and maintain that magnetism, they are classified as ferromagnetic materials.
- This classification explains their strength and various applications in technology and industry.
In summary, Neodymium and Samarium-cobalt magnets are ferromagnetic due to their ability to be strongly magnetized and retain their magnetism, making them essential in many advanced applications.
At the magnetic North Pole of the Earth, what is the value of the angle of dip?- a)Zero
- b)Minimum
- c)Infinity
- d)Maximum
Correct answer is option 'D'. Can you explain this answer?
At the magnetic North Pole of the Earth, what is the value of the angle of dip?
a)
Zero
b)
Minimum
c)
Infinity
d)
Maximum
|
|
Shalini Patel answered |
Angle of dip is 90o at geographical North Pole because attraction on the North Pole of needle is very strong and the needle remains in vertical plane. At the magnetic equator, the needle will point horizontally, i.e. dip angle is 0o. As you move from the magnetic equator towards the magnetic pole, the angle increases in the northern hemisphere. So, the angle of dip is maximum.
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.Assertion : We cannot think of a magnetic field configuration with three polesReason : A bar magnet does exert a torque on itself due to its own field.- a)If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
- b)If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
- c)If the Assertion is correct but Reason is incorrect.
- d)If both the Assertion and Reason are incorrect.
Correct answer is option 'D'. Can you explain this answer?
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
Assertion : We cannot think of a magnetic field configuration with three poles
Reason : A bar magnet does exert a torque on itself due to its own field.
a)
If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
b)
If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
c)
If the Assertion is correct but Reason is incorrect.
d)
If both the Assertion and Reason are incorrect.
|
|
Hansa Sharma answered |
It is quite clear that magnetic poles always exists in pairs. Since, one can imagine magnetic field configuration with three poles. When north poles or south poles of two magnets are glued together. They provide a three pole field configuration. It is also know that a bar magnet does not exert a torque on itself due to its own field.
Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Ferromagnetic substances become paramagnetic beyond Curie temperature.Reason (R): Domains are destroyed at high temperature.- a)Both A and R are true and R is the correct explanation of A
- b)Both A and R are true but R is NOT the correct explanation of A
- c)A is true but R is false
- d)A is false and R is true
Correct answer is option 'A'. Can you explain this answer?
Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Ferromagnetic substances become paramagnetic beyond Curie temperature.
Reason (R): Domains are destroyed at high temperature.
a)
Both A and R are true and R is the correct explanation of A
b)
Both A and R are true but R is NOT the correct explanation of A
c)
A is true but R is false
d)
A is false and R is true
|
|
Shalini Patel answered |
From Curie Weiss law,
As temperature increases beyond Curie temperature, susceptibility decreases and the ferromagnetic substances become paramagnetic. So, the assertion is true. Paramagnetic substance has no magnetic domain. At a very high temperature, the domains of ferromagnetic substance get destroyed and the substance transforms into paramagnetic substance. So, the reason is also true and properly explains the assertion.
Read the following text and answer the following questions on the basis of the same:Earth’s magnetism: Earth’s magnetic field is caused by a dynamo effect. The effect works in the same way as a dynamo light on a bicycle. Magnets in the dynamo start spinning when the bicycle is pedaled, creating an electric current. The electricity is then used to turn on the light. This process also works in reverse. If you have a rotating electric current, it will create a magnetic field. On Earth, flowing of liquid metal in the outer core of the planet generates electric currents. The rotation of Earth on its axis causes these electric currents to form a magnetic field which extends around the planet. The average magnetic field strength in the Earth's outer core was measured to be 25 Gauss, 50 times stronger than the magnetic field at the surface. The magnetic field is extremely important for sustaining life on Earth. Without it, we would be exposed to high amounts of radiation from the Sun and our atmosphere would be free to leak into space. This is likely what happened to the atmosphere on Mars. As Mars doesn’t have flowing liquid metal in its core, it doesn’t produce the same dynamo effect. This left the planet with a very weak magnetic field, allowing for its atmosphere to be stripped away by solar winds, leaving it uninhabitable. Based upon the study of lava flows throughout the world, it has been proposed that the Earth's magnetic field reverses at an average interval of approximately 300,000 years. However, the last such event occurred some 780,000 years ago.Electric current in the Earth’s body is generated due to:- a)movement of charged particle in the atmosphere.
- b)flowing of liquid metal in the outer core.
- c)electric discharges during thunderstorm.
- d)its revolution round the Sun.
Correct answer is option 'A'. Can you explain this answer?
Read the following text and answer the following questions on the basis of the same:
Earth’s magnetism: Earth’s magnetic field is caused by a dynamo effect. The effect works in the same way as a dynamo light on a bicycle. Magnets in the dynamo start spinning when the bicycle is pedaled, creating an electric current. The electricity is then used to turn on the light. This process also works in reverse. If you have a rotating electric current, it will create a magnetic field. On Earth, flowing of liquid metal in the outer core of the planet generates electric currents. The rotation of Earth on its axis causes these electric currents to form a magnetic field which extends around the planet. The average magnetic field strength in the Earth's outer core was measured to be 25 Gauss, 50 times stronger than the magnetic field at the surface. The magnetic field is extremely important for sustaining life on Earth. Without it, we would be exposed to high amounts of radiation from the Sun and our atmosphere would be free to leak into space. This is likely what happened to the atmosphere on Mars. As Mars doesn’t have flowing liquid metal in its core, it doesn’t produce the same dynamo effect. This left the planet with a very weak magnetic field, allowing for its atmosphere to be stripped away by solar winds, leaving it uninhabitable. Based upon the study of lava flows throughout the world, it has been proposed that the Earth's magnetic field reverses at an average interval of approximately 300,000 years. However, the last such event occurred some 780,000 years ago.
Electric current in the Earth’s body is generated due to:
a)
movement of charged particle in the atmosphere.
b)
flowing of liquid metal in the outer core.
c)
electric discharges during thunderstorm.
d)
its revolution round the Sun.
|
|
Gaurav Kumar answered |
On Earth, flowing of liquid metal in the outer core of the planet generates electric currents.
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.Assertion : The ferromagnetic substance do not obey Curie’s law.Reason : At Curie point a ferromagnetic substance start behaving as a paramagnetic substance.- a)If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
- b)If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
- c)If the Assertion is correct but Reason is incorrect.
- d)If both the Assertion and Reason are incorrect.
Correct answer is option 'B'. Can you explain this answer?
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
Assertion : The ferromagnetic substance do not obey Curie’s law.
Reason : At Curie point a ferromagnetic substance start behaving as a paramagnetic substance.
a)
If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
b)
If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
c)
If the Assertion is correct but Reason is incorrect.
d)
If both the Assertion and Reason are incorrect.
|
Harsh Mehta answered |
Assertion : The ferromagnetic substance do not obey Curie’s law.
Reason : At Curie point a ferromagnetic substance start behaving as a paramagnetic substance.
The correct answer to this question is option 'B', which states that both the Assertion and Reason are correct, but the Reason is not a correct explanation of the Assertion. Let's understand why this is the correct answer.
Explanation:
1. Understanding Curie's Law:
Curie's Law states that the magnetic susceptibility of a paramagnetic substance is inversely proportional to the absolute temperature. In other words, as the temperature increases, the magnetic susceptibility decreases. This law is valid for paramagnetic substances but not for ferromagnetic substances.
2. Assertion: The ferromagnetic substance do not obey Curie’s law.
The assertion is correct. Ferromagnetic substances do not follow Curie's Law. The magnetization of a ferromagnetic substance does not depend solely on temperature, as it does in paramagnetic substances.
3. Reason: At Curie point a ferromagnetic substance starts behaving as a paramagnetic substance.
The reason given is partially correct, but it does not provide a correct explanation for the assertion. The Curie point is the temperature at which a ferromagnetic substance loses its ferromagnetic properties and becomes paramagnetic. However, this does not mean that a ferromagnetic substance starts behaving as a paramagnetic substance at the Curie point.
4. Explanation:
Ferromagnetic substances exhibit strong permanent magnetization even in the absence of an external magnetic field. They have a characteristic property called hysteresis, which means that their magnetization depends not only on temperature but also on the history of the material. This hysteresis behavior is not accounted for by Curie's Law.
At temperatures below the Curie point, ferromagnetic substances have a spontaneous magnetization even in the absence of an external field. As the temperature increases towards the Curie point, the spontaneous magnetization decreases, and at the Curie point, it disappears completely. Above the Curie point, the substance becomes paramagnetic, which means that its magnetic properties are dominated by the influence of an external magnetic field.
Conclusion:
In conclusion, the assertion is correct that ferromagnetic substances do not obey Curie's Law. The reason provided is partially correct in stating that at the Curie point, a ferromagnetic substance loses its ferromagnetic properties and becomes paramagnetic. However, it does not provide a correct explanation for why ferromagnetic substances do not follow Curie's Law. Therefore, the correct answer is option 'B'.
Reason : At Curie point a ferromagnetic substance start behaving as a paramagnetic substance.
The correct answer to this question is option 'B', which states that both the Assertion and Reason are correct, but the Reason is not a correct explanation of the Assertion. Let's understand why this is the correct answer.
Explanation:
1. Understanding Curie's Law:
Curie's Law states that the magnetic susceptibility of a paramagnetic substance is inversely proportional to the absolute temperature. In other words, as the temperature increases, the magnetic susceptibility decreases. This law is valid for paramagnetic substances but not for ferromagnetic substances.
2. Assertion: The ferromagnetic substance do not obey Curie’s law.
The assertion is correct. Ferromagnetic substances do not follow Curie's Law. The magnetization of a ferromagnetic substance does not depend solely on temperature, as it does in paramagnetic substances.
3. Reason: At Curie point a ferromagnetic substance starts behaving as a paramagnetic substance.
The reason given is partially correct, but it does not provide a correct explanation for the assertion. The Curie point is the temperature at which a ferromagnetic substance loses its ferromagnetic properties and becomes paramagnetic. However, this does not mean that a ferromagnetic substance starts behaving as a paramagnetic substance at the Curie point.
4. Explanation:
Ferromagnetic substances exhibit strong permanent magnetization even in the absence of an external magnetic field. They have a characteristic property called hysteresis, which means that their magnetization depends not only on temperature but also on the history of the material. This hysteresis behavior is not accounted for by Curie's Law.
At temperatures below the Curie point, ferromagnetic substances have a spontaneous magnetization even in the absence of an external field. As the temperature increases towards the Curie point, the spontaneous magnetization decreases, and at the Curie point, it disappears completely. Above the Curie point, the substance becomes paramagnetic, which means that its magnetic properties are dominated by the influence of an external magnetic field.
Conclusion:
In conclusion, the assertion is correct that ferromagnetic substances do not obey Curie's Law. The reason provided is partially correct in stating that at the Curie point, a ferromagnetic substance loses its ferromagnetic properties and becomes paramagnetic. However, it does not provide a correct explanation for why ferromagnetic substances do not follow Curie's Law. Therefore, the correct answer is option 'B'.
Read the following text and answer the following questions on the basis of the same:Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories: (i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI). (ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.Super magnets are about _____ time stronger than ordinary magnets.- a)10
- b)100
- c)1000
- d)10000
Correct answer is option 'A'. Can you explain this answer?
Read the following text and answer the following questions on the basis of the same:
Super magnet The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. These elements can be magnetized, but have Curie temperatures below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, when they form compounds with transition metals such as iron, nickel, cobalt, etc. Curie temperature rises well above room temperature and they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used. Super magnets are of two categories: (i) Neodymium magnet: These are made from an alloy of neodymium, iron, and boron. This material is currently the strongest known type of permanent magnet. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI). (ii) Samarium-cobalt magnet: These are made from an alloy of samarium and cobalt. This second strongest type of rare Earth magnet is also used in electronic motors, turbo-machinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder. Since super magnets are about 10 times stronger than ordinary magnets, safe distance should be maintained otherwise these may damage mechanical watch, CRT monitor, pacemaker, credit cards, magnetically stored media etc. These types of magnets are hazardous for health also. The greater force exerted by rare-earth magnets creates hazards that are not seen with other types of magnet. Magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets or a magnet and a metal surface, even causing broken bones. Neodymium permanent magnets lose their magnetism 5% every 100 years. So, in the truest sense Neodymium magnets may be considered as a permanent magnet.
Super magnets are about _____ time stronger than ordinary magnets.
a)
10
b)
100
c)
1000
d)
10000
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Gaurav Kumar answered |
Super magnets are about 10 times stronger than ordinary magnets.
Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Gauss theorem is not applicable in magnetism.Reason (R): Magnetic monopole does not exist.- a)Both A and R are true and R is the correct explanation of A
- b)Both A and R are true but R is NOT the correct explanation of A
- c)A is true but R is false
- d)A is false and R is true
Correct answer is option 'A'. Can you explain this answer?
Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Gauss theorem is not applicable in magnetism.
Reason (R): Magnetic monopole does not exist.
a)
Both A and R are true and R is the correct explanation of A
b)
Both A and R are true but R is NOT the correct explanation of A
c)
A is true but R is false
d)
A is false and R is true
|
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Riya Banerjee answered |
Gauss's theorem of magnetism is different from that for electrostatics because electric charges may not exist in pair but magnetic poles always exist in pair. So assertion is true. Magnetic monopole does not exist. Magnetic poles always exist in pair. So reason is also true and reason clearly explains the assertion.
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