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Two inductances of 15 mH and 25 mH are connected in series such that their fluxes oppose each other. They are so placed that the coefficient of coupling is 0.8. The value of mutual inductance between them will be - a)15.5 mH
- b)18 mH
- c)12.6 mH
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
Two inductances of 15 mH and 25 mH are connected in series such that their fluxes oppose each other. They are so placed that the coefficient of coupling is 0.8. The value of mutual inductance between them will be
a)
15.5 mH
b)
18 mH
c)
12.6 mH
d)
None of these
|
Yash Patel answered |
Calculate the MMF when the magnetic flux is 5Wb and the reluctance is 3A/Wb.- a)10At
- b)10N
- c)15N
- d)15At
Correct answer is option 'D'. Can you explain this answer?
Calculate the MMF when the magnetic flux is 5Wb and the reluctance is 3A/Wb.
a)
10At
b)
10N
c)
15N
d)
15At
|
Sanya Agarwal answered |
We know that:
F = ϕS
Substituting the given values from the question, we get MMF = 15At.
F = ϕS
Substituting the given values from the question, we get MMF = 15At.
A coil of 100 turns is wound on a torroidal magnetic core having a reluctance of 104 AT/Wb. When the coil current is 5 A and is increasing at the rate of 200 A/s, the voltage across the coil would be (assume coil resistance to be 2 Ω)- a)210 volt
- b)230 volt
- c)115 volt
- d)Zero volt
Correct answer is option 'A'. Can you explain this answer?
A coil of 100 turns is wound on a torroidal magnetic core having a reluctance of 104 AT/Wb. When the coil current is 5 A and is increasing at the rate of 200 A/s, the voltage across the coil would be (assume coil resistance to be 2 Ω)
a)
210 volt
b)
230 volt
c)
115 volt
d)
Zero volt
|
|
Sanvi Kapoor answered |
The field winding of a dc electro-magnet is wound with 960 turns and has a resistance of 50 Ω. The excitation voltage is 230 V and the magnetic flux linking the coil is 5 mWb. The energy stored in the magnetic field is- a)22 Joules
- b)11 Joules
- c)19 Joules
- d)29 Joules
Correct answer is option 'B'. Can you explain this answer?
The field winding of a dc electro-magnet is wound with 960 turns and has a resistance of 50 Ω. The excitation voltage is 230 V and the magnetic flux linking the coil is 5 mWb. The energy stored in the magnetic field is
a)
22 Joules
b)
11 Joules
c)
19 Joules
d)
29 Joules
|
Charvi Reddy answered |
Current through the field winding,
So, energy stored in magnetic field
So, energy stored in magnetic field
The unit of magnetic flux is:- a)henry
- b)weber
- c)ampere turn/weber
- d)ampere/metre
Correct answer is option 'B'. Can you explain this answer?
The unit of magnetic flux is:
a)
henry
b)
weber
c)
ampere turn/weber
d)
ampere/metre
|
|
Sanya Agarwal answered |
- SI Unit of the magnetic flux is Weber.
- It is a vector quantity.
- It is measure by the equipment called as Fluxmeter.
- The magnetic flux per unit area is called as the flux density.
The property of a material which opposes the production of magnetic flux in it is known as:- a)mmf
- b)permeance
- c)permittivity
- d)reluctance
Correct answer is option 'D'. Can you explain this answer?
The property of a material which opposes the production of magnetic flux in it is known as:
a)
mmf
b)
permeance
c)
permittivity
d)
reluctance
|
|
Vaishnavi Singh answered |
Resistance in electrical circuit corresponds to reluctance in magnetic circuit. Reluctance opposes the production of magnetic flux in a magnetic circuit and resistance opposes the flow of current in electrical circuit.
The flux in a magnetic core is alternating sinusoidally at a frequency of 600 Hz. The maximum flux density is 2 Tesla and the eddy current loss is 15 Watts. What would be the eddy current loss in the core if the frequency is raised to 800 Hz and the maximum flux density is reduced to 1.5 Tesla?- a)12 Watts
- b)25.25 Watts
- c)15 Watts
- d)18 Watts
Correct answer is option 'C'. Can you explain this answer?
The flux in a magnetic core is alternating sinusoidally at a frequency of 600 Hz. The maximum flux density is 2 Tesla and the eddy current loss is 15 Watts. What would be the eddy current loss in the core if the frequency is raised to 800 Hz and the maximum flux density is reduced to 1.5 Tesla?
a)
12 Watts
b)
25.25 Watts
c)
15 Watts
d)
18 Watts
|
Aniket Choudhury answered |
We know that eddy current loss,
or
or
The emf induced in a conductor rotating in a bipolar field is- a)both dc and ac
- b)dconly
- c)ac only
- d)none of these
Correct answer is option 'C'. Can you explain this answer?
The emf induced in a conductor rotating in a bipolar field is
a)
both dc and ac
b)
dconly
c)
ac only
d)
none of these
|
Suyash Joshi answered |
As the field is bipolar, therefore the induced emf will be alternating in nature.
Air exhibits- a)ferromagnetism
- b)paramagnetism
- c)diamagnetism
- d)antiferromagnetism
Correct answer is option 'B'. Can you explain this answer?
Air exhibits
a)
ferromagnetism
b)
paramagnetism
c)
diamagnetism
d)
antiferromagnetism
|
Vaibhav Mukherjee answered |
Paramagnetism in Air Exhibits
Paramagnetism is a phenomenon in which a material is weakly attracted to an external magnetic field. This property is exhibited by materials that have unpaired electrons in their atomic or molecular orbitals. Air is a non-magnetic substance, but it exhibits paramagnetism under certain conditions.
Molecular Oxygen in Air
The main reason for the paramagnetism of air is the presence of molecular oxygen (O2) in the atmosphere. Oxygen molecules have two unpaired electrons in their outermost orbitals, which makes them weakly attracted to an external magnetic field.
The magnetic moments of the individual oxygen molecules in air are randomly oriented in the absence of an external magnetic field. However, when an external magnetic field is applied, the magnetic moments align themselves with the direction of the field, resulting in a weak attraction of air towards the field.
Temperature and Pressure
The extent of paramagnetism exhibited by air depends on the temperature and pressure of the gas. At higher temperatures, the thermal energy of the molecules overcomes the weak magnetic attraction, and the paramagnetism decreases. Similarly, at higher pressures, the molecules are closer together, and the interactions between them reduce the paramagnetic effect.
Applications
The paramagnetism of air has various applications in scientific research and technology. It is used in magnetic resonance imaging (MRI) to create high-resolution images of the human body. The paramagnetism of air is also used in the measurement of magnetic fields and in the separation of isotopes.
Conclusion
In conclusion, air exhibits paramagnetism due to the presence of molecular oxygen in the atmosphere. The paramagnetic effect of air depends on the temperature and pressure of the gas and has various applications in scientific research and technology.
Paramagnetism is a phenomenon in which a material is weakly attracted to an external magnetic field. This property is exhibited by materials that have unpaired electrons in their atomic or molecular orbitals. Air is a non-magnetic substance, but it exhibits paramagnetism under certain conditions.
Molecular Oxygen in Air
The main reason for the paramagnetism of air is the presence of molecular oxygen (O2) in the atmosphere. Oxygen molecules have two unpaired electrons in their outermost orbitals, which makes them weakly attracted to an external magnetic field.
The magnetic moments of the individual oxygen molecules in air are randomly oriented in the absence of an external magnetic field. However, when an external magnetic field is applied, the magnetic moments align themselves with the direction of the field, resulting in a weak attraction of air towards the field.
Temperature and Pressure
The extent of paramagnetism exhibited by air depends on the temperature and pressure of the gas. At higher temperatures, the thermal energy of the molecules overcomes the weak magnetic attraction, and the paramagnetism decreases. Similarly, at higher pressures, the molecules are closer together, and the interactions between them reduce the paramagnetic effect.
Applications
The paramagnetism of air has various applications in scientific research and technology. It is used in magnetic resonance imaging (MRI) to create high-resolution images of the human body. The paramagnetism of air is also used in the measurement of magnetic fields and in the separation of isotopes.
Conclusion
In conclusion, air exhibits paramagnetism due to the presence of molecular oxygen in the atmosphere. The paramagnetic effect of air depends on the temperature and pressure of the gas and has various applications in scientific research and technology.
Ohm’s law for magnetic circuits is _________.- a)F = ϕS
- b)F = ϕ/S
- c)F = ϕ2S
- d)F = ϕ/S2
Correct answer is option 'A'. Can you explain this answer?
Ohm’s law for magnetic circuits is _________.
a)
F = ϕS
b)
F = ϕ/S
c)
F = ϕ2S
d)
F = ϕ/S2
|
|
Naveen Mukherjee answered |
Ohm is the SI unit of electrical resistance. It is named after the German physicist Georg Simon Ohm. One ohm is defined as the resistance between two points in a conductor when a constant potential difference of one volt, applied to these points, produces a current of one ampere.
EMF induced in a coil rotating in a uniform magnetic field will be maximum when the- a)rate of cutting flux by the coil sides is minimum.
- b)flux linking with the coil is maximum.
- c)rate of change of flux linkage is minimum.
- d)none of the above
Correct answer is option 'D'. Can you explain this answer?
EMF induced in a coil rotating in a uniform magnetic field will be maximum when the
a)
rate of cutting flux by the coil sides is minimum.
b)
flux linking with the coil is maximum.
c)
rate of change of flux linkage is minimum.
d)
none of the above
|
Nitya Chopra answered |
Hence, emf induced is maximum when di/dt is maximum.
What happens to the MMF when the magnetic flux decreases?- a)Increases
- b)Decreases
- c)Remains constant
- d)Becomes zero
Correct answer is option 'B'. Can you explain this answer?
What happens to the MMF when the magnetic flux decreases?
a)
Increases
b)
Decreases
c)
Remains constant
d)
Becomes zero
|
|
Sanya Agarwal answered |
Ohm’s law for the magnetic circuit’s states that the MMF is directly proportional to the magnetic flux hence as the magnetic flux decreases, the MMF also decreases.
The laws of electromagnetic induction are summarized in the following equation:- a)
- b) e = iR
- c)
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
The laws of electromagnetic induction are summarized in the following equation:
a)
b)
e = iR
c)
d)
None of these
|
Kajal Mukherjee answered |
From Faraday’s law of electromagnetic induction,
(minus sign is due to Lenz’s law).
(minus sign is due to Lenz’s law).
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