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All questions of Magnetic Effects of Electric Current for Class 10 Exam
The magnetic field lines inside a long current-carrying solenoid are near-
- a)Straight
- b)Circular
- c)Elliptical
- d)Parabolic
Correct answer is option 'A'. Can you explain this answer?
The magnetic field lines inside a long current-carrying solenoid are near-
a)
Straight
b)
Circular
c)
Elliptical
d)
Parabolic
|
Gunjan Lakhani answered |
The field lines inside the solenoid are in the form of parallel straight lines. This indicates that the magnetic field is the same at all points inside the solenoid. That is, the field is uniform inside the solenoid.
Magnetic lines of force originate from the- a)North pole
- b)Center point
- c)South pole
- d)Either north pole or south pole
Correct answer is option 'A'. Can you explain this answer?
Magnetic lines of force originate from the
a)
North pole
b)
Center point
c)
South pole
d)
Either north pole or south pole
|
Ananya Das answered |
The direction of magnetic line of force is the direction of force on a North Pole, so the magnetic lines of force always begin on the North Pole of a magnet and end on the South Pole of the magnet. When a small magnetic compass is placed along a lie of force, it sets itself along the line tangential to it. Hence, the line drawn from the South Pole of the compass to its North pole shows the direction of the magnetic field.
An electric current flowing through a conductor produces
- a)Magnetic field
- b)Electric Field
- c)Electromagnetic field
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
An electric current flowing through a conductor produces
a)
Magnetic field
b)
Electric Field
c)
Electromagnetic field
d)
None of these
|
Vikas Kumar answered |
An electric current through a metallic conductor produces a magnetic field around it.
A magnetic field existing around a magnet can be represented by magnetic field lines. Magnetic field lines always form:- a)open loops
- b)closed loops
- c)straight lines
- d)Both closed loops and straight lines
Correct answer is option 'B'. Can you explain this answer?
A magnetic field existing around a magnet can be represented by magnetic field lines. Magnetic field lines always form:
a)
open loops
b)
closed loops
c)
straight lines
d)
Both closed loops and straight lines
|
Krishna Iyer answered |
Magnetic field lines can never cross, meaning that the field is unique at any point in space. Magnetic field lines are continuous, forming closed loops without beginning or end.
Overloading is due to- a)Insulation of wire is damaged
- b)fault in the appliances
- c)accidental hike in supply voltage
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
Overloading is due to
a)
Insulation of wire is damaged
b)
fault in the appliances
c)
accidental hike in supply voltage
d)
All of the above
|
Rohit Sharma answered |
Overloading occurs when there is any fault in the appliances or the insulation of wire got damaged. It also occurs when there is sudden hike in supply voltage.
Which of the following metal is not attracted by a magnet?- a)Cobalt
- b)Nickel
- c)Steel
- d)Silver
Correct answer is option 'D'. Can you explain this answer?
Which of the following metal is not attracted by a magnet?
a)
Cobalt
b)
Nickel
c)
Steel
d)
Silver
|
|
Ananya Das answered |
In the natural states, metals such as brass, copper , gold and silver will not attract magnets. This is because they are weak metals to start with. Magnets only attach themselves to strong metals such as iron and cobalt and that is why not all types of metals can make magnets stick to them.
Earth wire carries- a)current
- b)voltage
- c)no current
- d)heat
Correct answer is option 'C'. Can you explain this answer?
Earth wire carries
a)
current
b)
voltage
c)
no current
d)
heat
|
|
Kiran Mehta answered |
A "grounding" wire on the other hand is a safety wire that has intentionally been connected to earth. The grounding wire does not carry electricity under normal circuit operations. It's purpose is to carry electrical current only under short circuit or other conditions that would be potentially dangerous.
Can you explain the answer of this question below:A vertical wire carries a current straight down. To the east of this wire, the magnetic field points:
- A:
eastwards
- B:
downwards
- C:
southwards
- D:
northwards
The answer is c.
A vertical wire carries a current straight down. To the east of this wire, the magnetic field points:
eastwards
downwards
southwards
northwards
|
|
Anjana Khatri answered |
Use the right hand rule. Point your thumb down. Your fingers curl toward the south when you look on the east side of the wire.
What should be the core of an electromagnet?- a)soft iron
- b)hard iron
- c)rusted iron
- d)none of above
Correct answer is option 'A'. Can you explain this answer?
What should be the core of an electromagnet?
a)
soft iron
b)
hard iron
c)
rusted iron
d)
none of above
|
Chetna bhatia answered |
The core of an electromagnet should be a) soft iron.
Explanation: Soft iron is used as the core of an electromagnet because of its high magnetic permeability, meaning it can easily magnetize and demagnetize in response to an external magnetic field. When an electric current is passed through a coil wrapped around the soft iron core, it becomes strongly magnetized and creates a strong magnetic field. When the current is removed, the magnetism of the soft iron core quickly disappears, allowing the electromagnet to be turned on and off easily. Hard iron, on the other hand, retains its magnetism longer and is not suitable for electromagnets that need to be switched on and off frequently. Rusted iron is not ideal because the rust would interfere with the magnetic properties and reduce the efficiency of the electromagnet.
Explanation: Soft iron is used as the core of an electromagnet because of its high magnetic permeability, meaning it can easily magnetize and demagnetize in response to an external magnetic field. When an electric current is passed through a coil wrapped around the soft iron core, it becomes strongly magnetized and creates a strong magnetic field. When the current is removed, the magnetism of the soft iron core quickly disappears, allowing the electromagnet to be turned on and off easily. Hard iron, on the other hand, retains its magnetism longer and is not suitable for electromagnets that need to be switched on and off frequently. Rusted iron is not ideal because the rust would interfere with the magnetic properties and reduce the efficiency of the electromagnet.
Moving two like poles together usually causes a magnet resting on a table to repel and rotate. This occurs because:- a)Like magnetic poles repel
- b)Unlike magnetic poles attract
- c)Both of these
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
Moving two like poles together usually causes a magnet resting on a table to repel and rotate. This occurs because:
a)
Like magnetic poles repel
b)
Unlike magnetic poles attract
c)
Both of these
d)
None of these
|
Ishan Choudhury answered |
Like poles of magnet repel each other and unlike poles of magnet attract each other.
In Fleming’s left-hand rule the thumb indicates the direction of- a)magnetic field applied
- b)current flown in the conductor
- c)induced current
- d)mechanical force on the conductor
Correct answer is option 'D'. Can you explain this answer?
In Fleming’s left-hand rule the thumb indicates the direction of
a)
magnetic field applied
b)
current flown in the conductor
c)
induced current
d)
mechanical force on the conductor
|
|
Krishna Iyer answered |
In Fleming’s left-hand rule the thumb indicates the direction of mechanical force acting on the conductor. The forefinger points in the direction of magnetic field and the central finger in the direction of current flowing in the conductor.
If the circuit is closed and magnetic field lines are drawn over the horizontal plane ABCD, the lines are
- a)concentric circles
- b)elliptical in shape
- c)straight lines parallel to each other
- d)concentric circles near the point O but of elliptical shapes as we go away from it
Correct answer is option 'A'. Can you explain this answer?
If the circuit is closed and magnetic field lines are drawn over the horizontal plane ABCD, the lines are
a)
concentric circles
b)
elliptical in shape
c)
straight lines parallel to each other
d)
concentric circles near the point O but of elliptical shapes as we go away from it
|
|
Anita Menon answered |
- When a circuit carrying current is closed, it generates a magnetic field around it.
- According to Ampère's circuital law and the right-hand rule, the magnetic field lines around a straight current-carrying conductor form concentric circles.
- These circles are centered on the wire, and their planes are perpendicular to the direction of the current.
- Therefore, on a horizontal plane like ABCD, the magnetic field lines appear as concentric circles, making option A correct.
- According to Ampère's circuital law and the right-hand rule, the magnetic field lines around a straight current-carrying conductor form concentric circles.
- These circles are centered on the wire, and their planes are perpendicular to the direction of the current.
- Therefore, on a horizontal plane like ABCD, the magnetic field lines appear as concentric circles, making option A correct.
The strength of the magnetic field around a current-carrying straight conductor- a)is same every where around the conductor
- b)is directly proportional to the square of distance of a point from the conductor
- c)is directly proportional to the current flowing in the conductor
- d)is inversely proportional to the current
Correct answer is option 'C'. Can you explain this answer?
The strength of the magnetic field around a current-carrying straight conductor
a)
is same every where around the conductor
b)
is directly proportional to the square of distance of a point from the conductor
c)
is directly proportional to the current flowing in the conductor
d)
is inversely proportional to the current
|
|
Krishna Iyer answered |
The strength of the magnetic field around a current-carrying straight conductor is directly proportional to the amount of current flowing in the conductor.
When the direction of current through the conductor is reversed, the direction of- a)force is also reversed
- b)force remains same
- c)electromagnetic field is reversed
- d)electric field is also reversed
Correct answer is option 'A'. Can you explain this answer?
When the direction of current through the conductor is reversed, the direction of
a)
force is also reversed
b)
force remains same
c)
electromagnetic field is reversed
d)
electric field is also reversed
|
Drnitin Gopale answered |
Stretch out your hand as per Fleming left-hand rule and then tilt your hand upside down. You can see that the direction of mag field is the same, but the direction of current has reversed as per the question. also, the thumb goes downwards i.e opposite to initial direction. hence, we can see that the direction of force has been reversed.
Who has stated the Right hand Thumb Rule?- a)Orsted
- b)Fleming
- c)Einstein
- d)Maxwell
Correct answer is option 'D'. Can you explain this answer?
Who has stated the Right hand Thumb Rule?
a)
Orsted
b)
Fleming
c)
Einstein
d)
Maxwell
|
Asha Yadav answered |
B) Fleming
The right-hand thumb rule is a mnemonic technique used in electromagnetism to determine the direction of a magnetic field generated by a current-carrying conductor. It was first stated by John Ambrose Fleming, a British physicist and electrical engineer, in the late 19th century. The rule states that if the right hand is used to grip the conductor with the thumb pointing in the direction of the current flow, then the curled fingers will give the direction of the magnetic field.
The right-hand thumb rule is a mnemonic technique used in electromagnetism to determine the direction of a magnetic field generated by a current-carrying conductor. It was first stated by John Ambrose Fleming, a British physicist and electrical engineer, in the late 19th century. The rule states that if the right hand is used to grip the conductor with the thumb pointing in the direction of the current flow, then the curled fingers will give the direction of the magnetic field.
A constant current I flows through a horizontal metal wire in the plane of the paper from east to west as shown in the figure. The direction of magnetic field will be from north to south at a point :
- a)directly above the wire
- b)directly below the wire
- c)on the north side of the wire in the plane of the paper
- d)on the south side of the wire in the plane of the paper
Correct answer is option 'B'. Can you explain this answer?
A constant current I flows through a horizontal metal wire in the plane of the paper from east to west as shown in the figure. The direction of magnetic field will be from north to south at a point :
a)
directly above the wire
b)
directly below the wire
c)
on the north side of the wire in the plane of the paper
d)
on the south side of the wire in the plane of the paper
|
|
Ananya Das answered |
Let a constant current I flows through a horizontal wire from east to west. The direction of magnetic field, as per right-hand thumb rule, will be from north to south at a point directly below the current-carrying wire.
The area around a magnet, in which its influence (force of attraction or repulsion) can be felt, is called its- a)magnetic field
- b)magnetic strength
- c)magnetic power
- d)magnetic intensity
Correct answer is option 'A'. Can you explain this answer?
The area around a magnet, in which its influence (force of attraction or repulsion) can be felt, is called its
a)
magnetic field
b)
magnetic strength
c)
magnetic power
d)
magnetic intensity
|
|
Akshara kulkarni answered |
The region around a magnet, in which its influence can be felt, is called its magnetic field
Choose the wrong statement out of the following :- a)Magnetic poles always exist in pairs
- b)Magnetic poles must have same magnetic strength
- c)Like magnetic poles attract each other
- d)Unlike magnetic poles attract each other
Correct answer is option 'C'. Can you explain this answer?
Choose the wrong statement out of the following :
a)
Magnetic poles always exist in pairs
b)
Magnetic poles must have same magnetic strength
c)
Like magnetic poles attract each other
d)
Unlike magnetic poles attract each other
|
|
Anoushka nair answered |
Like magnetic poles (say N- and N-poles) always repel each other.
The direction of magnetic field developed around a current-carrying conductor can be easily found by the use of- a)Right-hand thumb rule
- b)Left-hand thumb rule
- c)Fleming’s left-hand rule
- d)Fleming’s right-hand rule
Correct answer is option 'A'. Can you explain this answer?
The direction of magnetic field developed around a current-carrying conductor can be easily found by the use of
a)
Right-hand thumb rule
b)
Left-hand thumb rule
c)
Fleming’s left-hand rule
d)
Fleming’s right-hand rule
|
|
Arun Sharma answered |
The direction of magnetic field developed around a current-carrying conductor can be found by the use of right-hand thumb rule.
For a current in a long straight solenoid N-pole and S-poIe are created at the two ends. Among the following statements, the incorrect statement is- a)The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid.
- b)The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil.
- c)The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet.
- d)The N-pole and S-pole exchange position when the direction of current through the solenoid is reversed.
Correct answer is option 'C'. Can you explain this answer?
For a current in a long straight solenoid N-pole and S-poIe are created at the two ends. Among the following statements, the incorrect statement is
a)
The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid.
b)
The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil.
c)
The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet.
d)
The N-pole and S-pole exchange position when the direction of current through the solenoid is reversed.
|
|
Ananya Das answered |
A solenoid behaves like a bar magnet. Hence the pattern of magnetic field associated with solenoid and around the bar magnet is same.
The strength of magnetic field along the axis of a solenoid coil :- a)increases on increasing current flowing through the solenoid coil
- b)increases on increasing the number of turns in the solenoid coil
- c)increases on introducing a soft iron core inside the solenoid coil
- d)all of the above
Correct answer is option 'D'. Can you explain this answer?
The strength of magnetic field along the axis of a solenoid coil :
a)
increases on increasing current flowing through the solenoid coil
b)
increases on increasing the number of turns in the solenoid coil
c)
increases on introducing a soft iron core inside the solenoid coil
d)
all of the above
|
Pallavi kulkarni answered |
The strength of magnetic field along the axis of a solenoid coil increases on increasing the current flowing through the solenoid coil and on increasing the number of turns in the solenoid coil. Moreover, if a soft iron core is inserted inside the solenoid coil then magnetic field increases many fold.
Permanent magnets are made up of- a)Ferronite (alloy of Fe, Ni and Mg)
- b)Alnico (alloy of Al, Ni and Co)
- c)Iron ore
- d)Bauxite ore
Correct answer is option 'B'. Can you explain this answer?
Permanent magnets are made up of
a)
Ferronite (alloy of Fe, Ni and Mg)
b)
Alnico (alloy of Al, Ni and Co)
c)
Iron ore
d)
Bauxite ore
|
|
Amar agrawal answered |
Understanding Permanent Magnets
Permanent magnets are materials that maintain a persistent magnetic field without the need for an external power source. Various alloys are specifically engineered for magnetic properties, and one of the most notable is Alnico.
What is Alnico?
- Alnico is an alloy composed primarily of:
- Aluminum (Al)
- Nickel (Ni)
- Cobalt (Co)
- These elements are combined with smaller amounts of other metals, such as copper and iron, to enhance the magnetic properties.
Why Alnico is Used for Permanent Magnets?
- **Strong Magnetic Field**: Alnico magnets exhibit high magnetic strength, making them suitable for applications that require a robust magnetic field.
- **Temperature Stability**: They maintain their magnetic properties over a wide range of temperatures, which is crucial for many industrial applications.
- **Versatility**: Alnico magnets can be easily shaped into various forms, such as rods, discs, or irregular shapes, allowing for diverse applications.
Comparison with Other Options
- **Ferronite**: Although it is a magnetic material, ferronite is not commonly used for permanent magnets compared to Alnico.
- **Iron Ore**: This is a natural material and not an alloy; it requires processing to create magnets.
- **Bauxite Ore**: Primarily a source of aluminum, bauxite is not used to make permanent magnets.
Conclusion
Alnico, as an alloy of aluminum, nickel, and cobalt, stands out for its remarkable magnetic properties, making it the correct choice for permanent magnets. Its stability and strength make it widely used in various applications, from electric motors to sensors.
Permanent magnets are materials that maintain a persistent magnetic field without the need for an external power source. Various alloys are specifically engineered for magnetic properties, and one of the most notable is Alnico.
What is Alnico?
- Alnico is an alloy composed primarily of:
- Aluminum (Al)
- Nickel (Ni)
- Cobalt (Co)
- These elements are combined with smaller amounts of other metals, such as copper and iron, to enhance the magnetic properties.
Why Alnico is Used for Permanent Magnets?
- **Strong Magnetic Field**: Alnico magnets exhibit high magnetic strength, making them suitable for applications that require a robust magnetic field.
- **Temperature Stability**: They maintain their magnetic properties over a wide range of temperatures, which is crucial for many industrial applications.
- **Versatility**: Alnico magnets can be easily shaped into various forms, such as rods, discs, or irregular shapes, allowing for diverse applications.
Comparison with Other Options
- **Ferronite**: Although it is a magnetic material, ferronite is not commonly used for permanent magnets compared to Alnico.
- **Iron Ore**: This is a natural material and not an alloy; it requires processing to create magnets.
- **Bauxite Ore**: Primarily a source of aluminum, bauxite is not used to make permanent magnets.
Conclusion
Alnico, as an alloy of aluminum, nickel, and cobalt, stands out for its remarkable magnetic properties, making it the correct choice for permanent magnets. Its stability and strength make it widely used in various applications, from electric motors to sensors.
The strength of a magnetic field inside a long current-carrying straight solenoid coil is- a)more at the ends than at the centre
- b)minimum in the middle
- c)same at all points
- d)found to increase from one end to the other
Correct answer is option 'C'. Can you explain this answer?
The strength of a magnetic field inside a long current-carrying straight solenoid coil is
a)
more at the ends than at the centre
b)
minimum in the middle
c)
same at all points
d)
found to increase from one end to the other
|
|
Rajani dasgupta answered |
The strength of a magnetic field inside a long, current-carrying, straight solenoid is uniform at all points. Moreover, the field depends on the amount of current flowing and the number of turns in solenoid coil besides its length
The most important safety method used for protecting home appliances from short circuiting or overloading is- a)earthing
- b)use of fuse
- c)use of stabilizers
- d)use of electric meter
Correct answer is option 'B'. Can you explain this answer?
The most important safety method used for protecting home appliances from short circuiting or overloading is
a)
earthing
b)
use of fuse
c)
use of stabilizers
d)
use of electric meter
|
Niharika Mehta answered |
The most important safety, method used for protecting home appliances from short circuiting or overloading is the electric fuse. This is a safety device having thin wire of short length made of tin (25%) and lead (75%) alloy having low melting point around 200degree. The fuse wire is of chosen thickness, so as to fix its resistance and hence amount of heating on passage of a particular amount of current. Whenever current through the fuse exceeds the set limit, the fuse wire melts and breaks the circuit. This saves the main circuit components from damage.
A current-carrying conductor is placed perpendicular to the direction of a uniform magnetic field. The direction of force acting on the conductor due to magnetic field is given by- a)Maxwell’s cork screw rule
- b)Ampere’s rule
- c)Fleming’s left-hand rule
- d)Fleming’s right-hand rule
Correct answer is option 'C'. Can you explain this answer?
A current-carrying conductor is placed perpendicular to the direction of a uniform magnetic field. The direction of force acting on the conductor due to magnetic field is given by
a)
Maxwell’s cork screw rule
b)
Ampere’s rule
c)
Fleming’s left-hand rule
d)
Fleming’s right-hand rule
|
Parth Basu answered |
A current carrying conductor when placed at right angle to a magnetic field, experiences a force due to a which we get motion. The direction of the force is given by Fleming’s left hand rule.
Assertion (A): The direction of force on a current-carrying conductor placed in a magnetic field depends on the direction of both the current and the magnetic field.Reason (R): When the direction of the current through the conductor is perpendicular to the direction of the magnetic field, the force experienced by the conductor is at its maximum.- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If Assertion is true but Reason is false
- d)If both Assertion and Reason are false
Correct answer is option 'B'. Can you explain this answer?
Assertion (A): The direction of force on a current-carrying conductor placed in a magnetic field depends on the direction of both the current and the magnetic field.
Reason (R): When the direction of the current through the conductor is perpendicular to the direction of the magnetic field, the force experienced by the conductor is at its maximum.
a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If Assertion is true but Reason is false
d)
If both Assertion and Reason are false
|
Kamna Science Academy answered |
- The assertion that the force on a current-carrying conductor in a magnetic field depends on the directions of both the current and the magnetic field is correct. This relationship is described by the right-hand rule for the force on a current-carrying conductor in a magnetic field.
- The reason that the force is maximum when the current is perpendicular to the magnetic field is also correct. This is a fundamental principle of electromagnetism.
- However, the reason does not directly explain why the assertion is true. While it is true that the force is maximum when the current is perpendicular to the magnetic field, this fact alone does not fully explain the dependence of the force on the directions of both the current and the magnetic field. Hence, Option B is the correct answer.
Assertion (A): The magnetic field lines around a bar magnet are closed curves.Reason (R): Inside the magnet, the direction of field lines is from its south pole to its north pole.- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If Assertion is true but Reason is false
- d)If both Assertion and Reason are false
Correct answer is option 'B'. Can you explain this answer?
Assertion (A): The magnetic field lines around a bar magnet are closed curves.
Reason (R): Inside the magnet, the direction of field lines is from its south pole to its north pole.
a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If Assertion is true but Reason is false
d)
If both Assertion and Reason are false
|
Elite Coaching Classes answered |
- Assertion (A) is true; magnetic field lines around a bar magnet are indeed closed curves.
- Reason (R) is also true; inside the magnet, the direction of field lines runs from its south pole to its north pole.
- However, the Reason does not correctly explain Assertion, as the closure of field lines is a consequence of the overall magnetic field configuration rather than just the direction of the field lines inside the magnet.
Assertion (A): When a circular loop of wire lies in the plane of the table with current passing through it clockwise, the magnetic field direction inside and outside the loop can be determined using the right-hand rule.Reason (R): The magnetic field in a given region is uniform.- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If Assertion is true but Reason is false
- d)If both Assertion and Reason are false
Correct answer is option 'B'. Can you explain this answer?
Assertion (A): When a circular loop of wire lies in the plane of the table with current passing through it clockwise, the magnetic field direction inside and outside the loop can be determined using the right-hand rule.
Reason (R): The magnetic field in a given region is uniform.
a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If Assertion is true but Reason is false
d)
If both Assertion and Reason are false
|
|
Kavya Shah answered |
Assertion Analysis
The assertion states that when a circular loop of wire carries a clockwise current, the magnetic field direction inside and outside the loop can be determined using the right-hand rule. This is correct:
- When you curl the fingers of your right hand in the direction of the current (clockwise in this case), your thumb points downward, indicating that the magnetic field inside the loop is directed downwards.
- Outside the loop, the magnetic field lines point outwards, following the right-hand rule.
Thus, the assertion is true.
Reason Analysis
The reason provided claims that the magnetic field in a given region is uniform. This statement is not necessarily true:
- The magnetic field produced by a circular loop is not uniform; it varies in strength and direction depending on the position in relation to the loop.
- Inside the loop, the magnetic field is relatively uniform compared to the outside, but it is not uniform across the entire region.
Therefore, while the assertion is true, the reason is false.
Conclusion
Combining these analyses leads to the conclusion:
- Both the assertion and reason are not correctly aligned in terms of explanation.
- Thus, the correct answer is option 'B': both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
This separation of understanding clarifies the relationship between the magnetic field's behavior around a current-carrying loop and the misconceptions about uniformity in magnetic fields.
The assertion states that when a circular loop of wire carries a clockwise current, the magnetic field direction inside and outside the loop can be determined using the right-hand rule. This is correct:
- When you curl the fingers of your right hand in the direction of the current (clockwise in this case), your thumb points downward, indicating that the magnetic field inside the loop is directed downwards.
- Outside the loop, the magnetic field lines point outwards, following the right-hand rule.
Thus, the assertion is true.
Reason Analysis
The reason provided claims that the magnetic field in a given region is uniform. This statement is not necessarily true:
- The magnetic field produced by a circular loop is not uniform; it varies in strength and direction depending on the position in relation to the loop.
- Inside the loop, the magnetic field is relatively uniform compared to the outside, but it is not uniform across the entire region.
Therefore, while the assertion is true, the reason is false.
Conclusion
Combining these analyses leads to the conclusion:
- Both the assertion and reason are not correctly aligned in terms of explanation.
- Thus, the correct answer is option 'B': both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
This separation of understanding clarifies the relationship between the magnetic field's behavior around a current-carrying loop and the misconceptions about uniformity in magnetic fields.
What defines a solenoid in the context of magnetic fields?- a)A coil of a few circular turns
- b)A long, straight wire
- c)A coil of many circular turns of insulated wire
- d)A single loop of wire
Correct answer is option 'C'. Can you explain this answer?
What defines a solenoid in the context of magnetic fields?
a)
A coil of a few circular turns
b)
A long, straight wire
c)
A coil of many circular turns of insulated wire
d)
A single loop of wire
|
|
Elite Coaching Classes answered |
In the context of magnetic fields, a solenoid is defined as a coil of many circular turns of insulated wire. Solenoids are crucial components in electromagnets and various electrical devices due to their ability to generate strong and uniform magnetic fields.
Why does a compass needle get deflected when brought near a _____?- a)Plastic rod
- b)Bar magnet
- c)Conductor
- d)Resistor
Correct answer is option 'B'. Can you explain this answer?
Why does a compass needle get deflected when brought near a _____?
a)
Plastic rod
b)
Bar magnet
c)
Conductor
d)
Resistor
|
Bhaskar Chauhan answered |
Understanding Compass Needle Deflection
When a compass needle is brought near a bar magnet, it experiences a deflection due to the magnetic field generated by the magnet. Here’s a detailed explanation of this phenomenon:
Magnetic Field Interaction
- A bar magnet consists of two poles: a north pole and a south pole.
- The compass needle itself is a small magnet, with its own north and south poles.
- When the compass is brought close to the bar magnet, the magnetic field of the bar magnet influences the compass needle.
Deflection Mechanism
- The north pole of the compass needle is attracted or repelled depending on the orientation of the bar magnet’s poles.
- If the compass is near the north pole of the bar magnet, the north pole of the compass needle is attracted, causing it to point towards the bar magnet.
- Conversely, if the compass is near the south pole of the bar magnet, the north pole of the compass needle is repelled, resulting in a deflection in the opposite direction.
Comparison with Other Options
- Plastic Rod: It is non-magnetic and does not produce a magnetic field; hence, it does not affect the compass needle.
- Conductor: While conductors can carry current and create a magnetic field, they do not have a persistent magnetic field like a bar magnet unless current flows through them.
- Resistor: Similar to conductors, resistors do not produce a magnetic field unless they are part of a circuit with current.
Conclusion
The deflection of a compass needle when brought near a bar magnet is a direct result of the interaction between the magnetic fields of the magnet and the compass. This simple yet fundamental principle underlies many concepts in magnetism and is essential for understanding how magnetic forces operate in our environment.
When a compass needle is brought near a bar magnet, it experiences a deflection due to the magnetic field generated by the magnet. Here’s a detailed explanation of this phenomenon:
Magnetic Field Interaction
- A bar magnet consists of two poles: a north pole and a south pole.
- The compass needle itself is a small magnet, with its own north and south poles.
- When the compass is brought close to the bar magnet, the magnetic field of the bar magnet influences the compass needle.
Deflection Mechanism
- The north pole of the compass needle is attracted or repelled depending on the orientation of the bar magnet’s poles.
- If the compass is near the north pole of the bar magnet, the north pole of the compass needle is attracted, causing it to point towards the bar magnet.
- Conversely, if the compass is near the south pole of the bar magnet, the north pole of the compass needle is repelled, resulting in a deflection in the opposite direction.
Comparison with Other Options
- Plastic Rod: It is non-magnetic and does not produce a magnetic field; hence, it does not affect the compass needle.
- Conductor: While conductors can carry current and create a magnetic field, they do not have a persistent magnetic field like a bar magnet unless current flows through them.
- Resistor: Similar to conductors, resistors do not produce a magnetic field unless they are part of a circuit with current.
Conclusion
The deflection of a compass needle when brought near a bar magnet is a direct result of the interaction between the magnetic fields of the magnet and the compass. This simple yet fundamental principle underlies many concepts in magnetism and is essential for understanding how magnetic forces operate in our environment.
What is the potential difference of current in Indian household circuit?- a)220 V
- b)240 V
- c)330 V
- d)440 V
Correct answer is option 'A'. Can you explain this answer?
What is the potential difference of current in Indian household circuit?
a)
220 V
b)
240 V
c)
330 V
d)
440 V
|
|
Ritu Saxena answered |
Potential difference between a live wire and a neutral wire in a domestic circuits it 220 V and the frequency of an AC is 50 Hz.
The direction of magnetic field pattern produced by a straight wire can be determined with which one of the following rules ?- a)Thumb rule
- b)Fleming’s left hand rule
- c)Fleming’s right hand rule
- d)Any of the these
Correct answer is option 'A'. Can you explain this answer?
The direction of magnetic field pattern produced by a straight wire can be determined with which one of the following rules ?
a)
Thumb rule
b)
Fleming’s left hand rule
c)
Fleming’s right hand rule
d)
Any of the these
|
|
Pritam Sengupta answered |
A) Thumb rule
Electromagnet works on- a)Magnetic effect of current
- b)Electric effect of current
- c)Heating effect of current
- d)Chemical effect of current
Correct answer is option 'A'. Can you explain this answer?
Electromagnet works on
a)
Magnetic effect of current
b)
Electric effect of current
c)
Heating effect of current
d)
Chemical effect of current
|
|
Nisha Choudhury answered |
An electromagnet works on the magnetic effect of current. It has been found that if a soft iron rod called core is placed inside a solenoid, then the strength of the magnetic field becomes very large because the iron ore is magnetized by induction.
When a charged particle moves perpendicular to a magnetic field, then- a)Speed of the particle is changed
- b)Speed of the particle remains the same
- c)Direction of the particle remains unchanged
- d)Acceleration of the particle remain unchanged
Correct answer is option 'B'. Can you explain this answer?
When a charged particle moves perpendicular to a magnetic field, then
a)
Speed of the particle is changed
b)
Speed of the particle remains the same
c)
Direction of the particle remains unchanged
d)
Acceleration of the particle remain unchanged
|
Anika malhotra answered |
Explanation:
When a charged particle moves perpendicular to a magnetic field, the speed of the particle remains the same. This is known as the magnetic force or the Lorentz force.
Key Points:
The following factors contribute to the speed of the particle remaining the same:
1. Magnetic Force: When a charged particle moves perpendicular to a magnetic field, it experiences a force known as the magnetic force. This force acts at right angles to the motion of the particle and the magnetic field.
2. Circular Path: The magnetic force causes the charged particle to move in a circular path. This circular motion is due to the continuous deflection of the particle by the magnetic force.
3. Centripetal Force: In a circular motion, there is a force called the centripetal force that continuously pulls the particle towards the center of the circular path. This force is provided by the magnetic force acting as the centripetal force.
4. Constant Speed: The centripetal force required to keep the particle in a circular path is provided by the magnetic force. As long as the magnetic force remains constant, the speed of the particle remains the same.
5. No Change in Energy: Since the speed of the particle remains the same, there is no change in its kinetic energy. The work done by the magnetic force is zero, as the force is always perpendicular to the displacement of the particle.
Conclusion:
When a charged particle moves perpendicular to a magnetic field, the speed of the particle remains the same. This is due to the magnetic force causing the particle to move in a circular path, with the centripetal force provided by the magnetic force. As a result, there is no change in the speed or kinetic energy of the particle.
When a charged particle moves perpendicular to a magnetic field, the speed of the particle remains the same. This is known as the magnetic force or the Lorentz force.
Key Points:
The following factors contribute to the speed of the particle remaining the same:
1. Magnetic Force: When a charged particle moves perpendicular to a magnetic field, it experiences a force known as the magnetic force. This force acts at right angles to the motion of the particle and the magnetic field.
2. Circular Path: The magnetic force causes the charged particle to move in a circular path. This circular motion is due to the continuous deflection of the particle by the magnetic force.
3. Centripetal Force: In a circular motion, there is a force called the centripetal force that continuously pulls the particle towards the center of the circular path. This force is provided by the magnetic force acting as the centripetal force.
4. Constant Speed: The centripetal force required to keep the particle in a circular path is provided by the magnetic force. As long as the magnetic force remains constant, the speed of the particle remains the same.
5. No Change in Energy: Since the speed of the particle remains the same, there is no change in its kinetic energy. The work done by the magnetic force is zero, as the force is always perpendicular to the displacement of the particle.
Conclusion:
When a charged particle moves perpendicular to a magnetic field, the speed of the particle remains the same. This is due to the magnetic force causing the particle to move in a circular path, with the centripetal force provided by the magnetic force. As a result, there is no change in the speed or kinetic energy of the particle.
Which of the following statement concerning magnetic field is correct ?
(1) The part of a bar magnet, at which the magnetic field is the strongest, is called its pole.
(2) A magnetic field is present near a compass needle.
(3) There is no magnetic field inside a current-carrying solenoid.- a)(1) and (2) only
- b)(2) and (3) only
- c)(2) only
- d)(1) only
Correct answer is option 'A'. Can you explain this answer?
Which of the following statement concerning magnetic field is correct ?
(1) The part of a bar magnet, at which the magnetic field is the strongest, is called its pole.
(2) A magnetic field is present near a compass needle.
(3) There is no magnetic field inside a current-carrying solenoid.
(1) The part of a bar magnet, at which the magnetic field is the strongest, is called its pole.
(2) A magnetic field is present near a compass needle.
(3) There is no magnetic field inside a current-carrying solenoid.
a)
(1) and (2) only
b)
(2) and (3) only
c)
(2) only
d)
(1) only
|
Crafty Classes answered |
Statement (1) is correct: A bar magnet has two poles - a north pole and a south pole. The magnetic field is strongest near these poles.
Statement (2) is also correct: A compass needle aligns itself with the Earth's magnetic field, and it points towards the Earth's magnetic north. This indicates the presence of a magnetic field around the Earth.
Statement (3) is incorrect: In fact, a current-carrying solenoid produces a strong magnetic field inside it. The direction of the magnetic field can be determined using the right-hand thumb rule.
Statement (2) is also correct: A compass needle aligns itself with the Earth's magnetic field, and it points towards the Earth's magnetic north. This indicates the presence of a magnetic field around the Earth.
Statement (3) is incorrect: In fact, a current-carrying solenoid produces a strong magnetic field inside it. The direction of the magnetic field can be determined using the right-hand thumb rule.
What happens to the direction of the force on a current-carrying conductor when the direction of the current is reversed, while the magnetic field remains unchanged?- a)The direction of the force remains the same.
- b)The direction of the force is reversed.
- c)The magnitude of the force is doubled.
- d)The force becomes zero.
Correct answer is option 'B'. Can you explain this answer?
a)
The direction of the force remains the same.
b)
The direction of the force is reversed.
c)
The magnitude of the force is doubled.
d)
The force becomes zero.
|
Ciel Knowledge answered |
According to Fleming's left-hand rule, if the direction of the current is reversed while keeping the magnetic field unchanged, the direction of the force on the conductor is also reversed.
Which property of a proton can change while it moves freely in a magnetic field?- a)mass
- b)speed
- c)velocity
- d)momentum
Correct answer is option 'C'. Can you explain this answer?
Which property of a proton can change while it moves freely in a magnetic field?
a)
mass
b)
speed
c)
velocity
d)
momentum
|
|
Elite Coaching Classes answered |
When a proton moves freely in a magnetic field, its velocity can change. This change occurs due to the interaction between the magnetic field and the moving charge, leading to alterations in the proton's direction and speed.
Assertion (A): A metallic wire carrying an electric current has associated with it a magnetic field.Reason (R): The field lines about the wire consist of a series of concentric circles whose direction is given by the right-hand rule.- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If Assertion is true but Reason is false
- d)If both Assertion and Reason are false
Correct answer is option 'B'. Can you explain this answer?
Assertion (A): A metallic wire carrying an electric current has associated with it a magnetic field.
Reason (R): The field lines about the wire consist of a series of concentric circles whose direction is given by the right-hand rule.
a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If Assertion is true but Reason is false
d)
If both Assertion and Reason are false
|
|
Anjana Chavan answered |
Understanding the Assertion and Reason
The statement provided includes two components: an Assertion (A) about a metallic wire carrying current and a Reason (R) explaining the nature of the magnetic field around it.
Assertion (A):
- A metallic wire carrying an electric current does indeed generate a magnetic field. This phenomenon is a fundamental principle of electromagnetism, confirmed by experimental evidence.
Reason (R):
- The magnetic field lines around the wire are indeed in the form of concentric circles. The direction of these field lines can be determined using the right-hand rule: if you point your thumb in the direction of the current, your fingers curl in the direction of the magnetic field lines.
Why Option B is Correct
- Both the Assertion and the Reason are true statements. However, the Reason does not directly explain the Assertion. The Assertion is a general fact about electric currents and magnetic fields, while the Reason describes a specific characteristic of the magnetic field produced by the current.
- The relationship is that the magnetic field exists due to the current (Assertion), and the right-hand rule helps visualize this magnetic field (Reason). Thus, while the Reason elaborates on the nature of the magnetic field, it does not explain why the magnetic field exists.
Conclusion
- Therefore, the correct answer is option B: both Assertion and Reason are true, but Reason is not the correct explanation of Assertion. This highlights the distinction between a phenomenon and its descriptive characteristics.
The statement provided includes two components: an Assertion (A) about a metallic wire carrying current and a Reason (R) explaining the nature of the magnetic field around it.
Assertion (A):
- A metallic wire carrying an electric current does indeed generate a magnetic field. This phenomenon is a fundamental principle of electromagnetism, confirmed by experimental evidence.
Reason (R):
- The magnetic field lines around the wire are indeed in the form of concentric circles. The direction of these field lines can be determined using the right-hand rule: if you point your thumb in the direction of the current, your fingers curl in the direction of the magnetic field lines.
Why Option B is Correct
- Both the Assertion and the Reason are true statements. However, the Reason does not directly explain the Assertion. The Assertion is a general fact about electric currents and magnetic fields, while the Reason describes a specific characteristic of the magnetic field produced by the current.
- The relationship is that the magnetic field exists due to the current (Assertion), and the right-hand rule helps visualize this magnetic field (Reason). Thus, while the Reason elaborates on the nature of the magnetic field, it does not explain why the magnetic field exists.
Conclusion
- Therefore, the correct answer is option B: both Assertion and Reason are true, but Reason is not the correct explanation of Assertion. This highlights the distinction between a phenomenon and its descriptive characteristics.
In case of a current-carrying circular coil, the magnetic field is maximum- a)At its centre
- b)At the ends of the coil
- c)Any where inside the coil
- d)Outside the coil
Correct answer is option 'A'. Can you explain this answer?
In case of a current-carrying circular coil, the magnetic field is maximum
a)
At its centre
b)
At the ends of the coil
c)
Any where inside the coil
d)
Outside the coil
|
|
Vivek Bansal answered |
The two magnetic fields, each due to the semicircular segment of the coil through A and B, assist each other as we move towards the centre of the coil.
The magnetic field inside a long straight solenoid-carrying current _____.- a)is zero.
- b)decreases as we move towards its end.
- c)increases as we move towards its end.
- d)is the same at all points.
Correct answer is option 'D'. Can you explain this answer?
The magnetic field inside a long straight solenoid-carrying current _____.
a)
is zero.
b)
decreases as we move towards its end.
c)
increases as we move towards its end.
d)
is the same at all points.
|
|
Elite Coaching Classes answered |
The magnetic field inside a long straight solenoid carrying current is the same at all points. This characteristic of a solenoid's magnetic field is a key property that remains consistent along its length, providing uniformity in the field distribution.
The magnetic field inside a long straight solenoid carrying current _____.- a)is zero
- b)decreases as we move towards its end
- c)increases as we move towards its end
- d)is the same at all points
Correct answer is option 'D'. Can you explain this answer?
The magnetic field inside a long straight solenoid carrying current _____.
a)
is zero
b)
decreases as we move towards its end
c)
increases as we move towards its end
d)
is the same at all points
|
Top Rankers answered |
The magnetic field inside a long straight solenoid carrying current is the same at all points. This characteristic is a key property of the magnetic field produced by such a configuration.
What is the current rating of power switch current in our household circuit?- a)5 A
- b)10 A
- c)15 A
- d)20 A
Correct answer is option 'C'. Can you explain this answer?
What is the current rating of power switch current in our household circuit?
a)
5 A
b)
10 A
c)
15 A
d)
20 A
|
|
Mira nambiar answered |
Understanding Household Circuit Ratings
In most household circuits, the power switch current rating is crucial for ensuring safety and efficiency. The common ratings you might encounter include 5 A, 10 A, 15 A, and 20 A.
Standard Current Ratings
- 5 A: This rating is typically used for low-power devices such as lamps and small electronics.
- 10 A: This can handle moderate loads like kitchen appliances, but it’s not sufficient for higher power devices.
- 15 A: This is the most common rating for a standard household circuit in many countries. It can effectively support larger appliances like refrigerators, microwaves, and washing machines.
- 20 A: This is used for heavy-duty appliances, such as air conditioners or electric ovens, which require more current to operate safely.
Why is 15 A the Correct Answer?
The choice of 15 A as the standard rating stems from the need for balance between safety and functionality:
- Safety: A 15 A rating prevents overheating and potential fire hazards by limiting the current that can flow through the circuit.
- Versatility: It provides adequate supply for a variety of household appliances without the risk of overloading the circuit.
Conclusion
In summary, while 5 A and 10 A are suitable for low to moderate power devices, the 15 A rating is widely adopted for general household use, accommodating a range of appliances safely. The 20 A rating is reserved for specialized, high-power equipment.
In most household circuits, the power switch current rating is crucial for ensuring safety and efficiency. The common ratings you might encounter include 5 A, 10 A, 15 A, and 20 A.
Standard Current Ratings
- 5 A: This rating is typically used for low-power devices such as lamps and small electronics.
- 10 A: This can handle moderate loads like kitchen appliances, but it’s not sufficient for higher power devices.
- 15 A: This is the most common rating for a standard household circuit in many countries. It can effectively support larger appliances like refrigerators, microwaves, and washing machines.
- 20 A: This is used for heavy-duty appliances, such as air conditioners or electric ovens, which require more current to operate safely.
Why is 15 A the Correct Answer?
The choice of 15 A as the standard rating stems from the need for balance between safety and functionality:
- Safety: A 15 A rating prevents overheating and potential fire hazards by limiting the current that can flow through the circuit.
- Versatility: It provides adequate supply for a variety of household appliances without the risk of overloading the circuit.
Conclusion
In summary, while 5 A and 10 A are suitable for low to moderate power devices, the 15 A rating is widely adopted for general household use, accommodating a range of appliances safely. The 20 A rating is reserved for specialized, high-power equipment.
A straight wire of mass 200 g and length 1.5 m carries a current of 2A. It is suspended in mid air by a uniform horizontal magnetic field whose magnitude in Tesla is- a)2 T
- b)0.65 T
- c)1.3 T
- d)0.55 T
Correct answer is option 'B'. Can you explain this answer?
A straight wire of mass 200 g and length 1.5 m carries a current of 2A. It is suspended in mid air by a uniform horizontal magnetic field whose magnitude in Tesla is
a)
2 T
b)
0.65 T
c)
1.3 T
d)
0.55 T
|
Prabhat mehta answered |
Given information:
- Mass of the wire (m) = 200 g = 0.2 kg
- Length of the wire (L) = 1.5 m
- Current flowing through the wire (I) = 2 A
To find: The magnitude of the magnetic field (B) in Tesla.
Formula used:
The magnetic force on a current-carrying wire in a magnetic field is given by the formula:
F = BIL sinθ
Where:
- F is the force on the wire,
- B is the magnetic field strength,
- I is the current in the wire,
- L is the length of the wire, and
- θ is the angle between the magnetic field and the wire.
Since the wire is in mid-air and suspended, the force acting on it is only due to the magnetic field. The weight of the wire is balanced by the tension in the wire, so there is no net force in the vertical direction. Therefore, the force due to the magnetic field must be equal and opposite to the weight of the wire.
The weight of the wire can be calculated using the formula:
Weight = mass * gravity
Where:
- The mass of the wire (m) is given as 0.2 kg, and
- The acceleration due to gravity (g) is approximately 9.8 m/s².
Calculation:
Weight = 0.2 kg * 9.8 m/s² = 1.96 N
Since the magnetic force is equal and opposite to the weight, we have:
F = 1.96 N
Using the formula F = BIL sinθ, we can rearrange it to solve for B:
B = F / (IL sinθ)
In this case, the wire is suspended in mid-air, so the angle θ between the magnetic field and the wire is 90°. Therefore, sinθ = 1.
B = F / (IL * 1)
B = F / IL
Substituting the given values:
B = 1.96 N / (2 A * 1.5 m)
B = 1.96 N / 3 A·m
B = 0.65 T
Hence, the magnitude of the magnetic field is 0.65 T, which corresponds to option 'B'.
- Mass of the wire (m) = 200 g = 0.2 kg
- Length of the wire (L) = 1.5 m
- Current flowing through the wire (I) = 2 A
To find: The magnitude of the magnetic field (B) in Tesla.
Formula used:
The magnetic force on a current-carrying wire in a magnetic field is given by the formula:
F = BIL sinθ
Where:
- F is the force on the wire,
- B is the magnetic field strength,
- I is the current in the wire,
- L is the length of the wire, and
- θ is the angle between the magnetic field and the wire.
Since the wire is in mid-air and suspended, the force acting on it is only due to the magnetic field. The weight of the wire is balanced by the tension in the wire, so there is no net force in the vertical direction. Therefore, the force due to the magnetic field must be equal and opposite to the weight of the wire.
The weight of the wire can be calculated using the formula:
Weight = mass * gravity
Where:
- The mass of the wire (m) is given as 0.2 kg, and
- The acceleration due to gravity (g) is approximately 9.8 m/s².
Calculation:
Weight = 0.2 kg * 9.8 m/s² = 1.96 N
Since the magnetic force is equal and opposite to the weight, we have:
F = 1.96 N
Using the formula F = BIL sinθ, we can rearrange it to solve for B:
B = F / (IL sinθ)
In this case, the wire is suspended in mid-air, so the angle θ between the magnetic field and the wire is 90°. Therefore, sinθ = 1.
B = F / (IL * 1)
B = F / IL
Substituting the given values:
B = 1.96 N / (2 A * 1.5 m)
B = 1.96 N / 3 A·m
B = 0.65 T
Hence, the magnitude of the magnetic field is 0.65 T, which corresponds to option 'B'.
Commercial electric motors do not use- a)An electromagnet to rotate the armature
- b)Effectively large number of turns of conducting wire in the current-carrying coil
- c)A permanent magnet to rotate the armature
- d)A soft iron core on which the coil is wound
Correct answer is option 'C'. Can you explain this answer?
Commercial electric motors do not use
a)
An electromagnet to rotate the armature
b)
Effectively large number of turns of conducting wire in the current-carrying coil
c)
A permanent magnet to rotate the armature
d)
A soft iron core on which the coil is wound
|
|
Gopika dasgupta answered |
Understanding Electric Motors
Electric motors are devices that convert electrical energy into mechanical energy using electromagnetic principles. In commercial electric motors, various components play crucial roles in their functionality.
Components of Electric Motors
- Electromagnet:
- Most electric motors use electromagnets to generate the magnetic field required for rotation. This field interacts with the armature to produce motion.
- Conducting Wire:
- A large number of turns of conducting wire are used in the coil. This increases the magnetic field strength when electric current passes through, enhancing the motor's efficiency.
- Soft Iron Core:
- The coil is often wound around a soft iron core, which amplifies the magnetic field. This core helps in directing the magnetic lines of force, improving the motor's performance.
Why Permanent Magnets Are Less Common
- Permanent Magnet Use:
- In commercial electric motors, the use of permanent magnets to rotate the armature is not typical. While some motors, like small DC motors, might feature permanent magnets, most larger and more complex motors rely on electromagnets for better control and efficiency.
- Flexibility and Control:
- Electromagnets allow for adjustable magnetic fields, which enable precise control over speed and torque. This flexibility is essential in industrial applications, making electromagnets more favorable than permanent magnets.
Conclusion
In summary, commercial electric motors primarily utilize electromagnets, conducting wire coils, and soft iron cores, rather than permanent magnets, to achieve efficient and controllable motion. Thus, the correct answer to the question is option 'C'.
Electric motors are devices that convert electrical energy into mechanical energy using electromagnetic principles. In commercial electric motors, various components play crucial roles in their functionality.
Components of Electric Motors
- Electromagnet:
- Most electric motors use electromagnets to generate the magnetic field required for rotation. This field interacts with the armature to produce motion.
- Conducting Wire:
- A large number of turns of conducting wire are used in the coil. This increases the magnetic field strength when electric current passes through, enhancing the motor's efficiency.
- Soft Iron Core:
- The coil is often wound around a soft iron core, which amplifies the magnetic field. This core helps in directing the magnetic lines of force, improving the motor's performance.
Why Permanent Magnets Are Less Common
- Permanent Magnet Use:
- In commercial electric motors, the use of permanent magnets to rotate the armature is not typical. While some motors, like small DC motors, might feature permanent magnets, most larger and more complex motors rely on electromagnets for better control and efficiency.
- Flexibility and Control:
- Electromagnets allow for adjustable magnetic fields, which enable precise control over speed and torque. This flexibility is essential in industrial applications, making electromagnets more favorable than permanent magnets.
Conclusion
In summary, commercial electric motors primarily utilize electromagnets, conducting wire coils, and soft iron cores, rather than permanent magnets, to achieve efficient and controllable motion. Thus, the correct answer to the question is option 'C'.
An electric bulb rated 220 V is connected to 220 V, 5 Hz AC source. The bulb- a)Does not glow
- b)Glows immediately
- c)Glows continuously
- d)Gets fused
Correct answer is option 'B'. Can you explain this answer?
An electric bulb rated 220 V is connected to 220 V, 5 Hz AC source. The bulb
a)
Does not glow
b)
Glows immediately
c)
Glows continuously
d)
Gets fused
|
Sudha gupta answered |
Explanation:
The given question is related to the working of an electric bulb when connected to an AC source. Let us understand the answer to the question in detail.
The working of an electric bulb:
An electric bulb consists of a filament made up of tungsten wire which is enclosed in a glass bulb filled with an inert gas like argon. When an electric current flows through the filament, it gets heated up and produces light. The amount of light produced depends on the temperature of the filament. When the temperature of the filament reaches a certain level, it starts glowing and emits light.
Working of AC source:
An AC source is a source of electrical energy that produces an alternating current. In an AC source, the direction of current changes periodically. The frequency of the current is measured in Hertz (Hz) and indicates the number of cycles per second.
Answer to the question:
When an electric bulb rated 220 V is connected to a 220 V, 5 Hz AC source, the bulb glows immediately. This is because the voltage of the AC source is equal to the rated voltage of the bulb. As soon as the current flows through the filament, it gets heated up and starts emitting light. The frequency of the AC source does not affect the working of the bulb as long as the voltage is within the rated value.
Options other than B:
a) Does not glow: This option is incorrect as the bulb will glow when connected to an AC source of the same voltage.
c) Glows continuously: This option is incorrect as the bulb will glow as long as it is connected to the AC source. It will not glow continuously without any power source.
d) Gets fused: This option is incorrect as the bulb will not get fused unless the voltage of the AC source exceeds the rated voltage of the bulb.
Conclusion:
In conclusion, an electric bulb rated 220 V will immediately start glowing when connected to a 220 V, 5 Hz AC source. The frequency of the AC source does not affect the working of the bulb as long as the voltage is within the rated value.
The given question is related to the working of an electric bulb when connected to an AC source. Let us understand the answer to the question in detail.
The working of an electric bulb:
An electric bulb consists of a filament made up of tungsten wire which is enclosed in a glass bulb filled with an inert gas like argon. When an electric current flows through the filament, it gets heated up and produces light. The amount of light produced depends on the temperature of the filament. When the temperature of the filament reaches a certain level, it starts glowing and emits light.
Working of AC source:
An AC source is a source of electrical energy that produces an alternating current. In an AC source, the direction of current changes periodically. The frequency of the current is measured in Hertz (Hz) and indicates the number of cycles per second.
Answer to the question:
When an electric bulb rated 220 V is connected to a 220 V, 5 Hz AC source, the bulb glows immediately. This is because the voltage of the AC source is equal to the rated voltage of the bulb. As soon as the current flows through the filament, it gets heated up and starts emitting light. The frequency of the AC source does not affect the working of the bulb as long as the voltage is within the rated value.
Options other than B:
a) Does not glow: This option is incorrect as the bulb will glow when connected to an AC source of the same voltage.
c) Glows continuously: This option is incorrect as the bulb will glow as long as it is connected to the AC source. It will not glow continuously without any power source.
d) Gets fused: This option is incorrect as the bulb will not get fused unless the voltage of the AC source exceeds the rated voltage of the bulb.
Conclusion:
In conclusion, an electric bulb rated 220 V will immediately start glowing when connected to a 220 V, 5 Hz AC source. The frequency of the AC source does not affect the working of the bulb as long as the voltage is within the rated value.
An electric fuse prevents damage to the appliances and circuits due to ____.- a)Overvoltage
- b)Short-circuiting
- c)Power surges
- d)Underloading
Correct answer is option 'B'. Can you explain this answer?
An electric fuse prevents damage to the appliances and circuits due to ____.
a)
Overvoltage
b)
Short-circuiting
c)
Power surges
d)
Underloading
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Elite Coaching Classes answered |
An electric fuse prevents damage to the appliances and circuits due to short-circuiting, which can occur when the live wire and the neutral wire come into direct contact, causing an abrupt increase in current flow.
If a current-carrying conductor is placed in a uniform magnetic field and oriented parallel to the magnetic field lines, what happens to the force on the conductor?- a)The force is at its maximum.
- b)The force is zero.
- c)The force is doubled.
- d)The force becomes perpendicular to the field.
Correct answer is option 'B'. Can you explain this answer?
If a current-carrying conductor is placed in a uniform magnetic field and oriented parallel to the magnetic field lines, what happens to the force on the conductor?
a)
The force is at its maximum.
b)
The force is zero.
c)
The force is doubled.
d)
The force becomes perpendicular to the field.
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Top Rankers answered |
When a current-carrying conductor is oriented parallel to the magnetic field lines, the force experienced by the conductor is zero. This is because the force on the conductor is given by F=BILsinθ, where θ is the angle between the direction of the current and the magnetic field. When θ is 0 degrees (parallel), sinθ is zero, resulting in no force.
To which wire amongst the following, an electric fuse connected?- a)Neutral
- b)Earth
- c)Live
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
To which wire amongst the following, an electric fuse connected?
a)
Neutral
b)
Earth
c)
Live
d)
None of these
|
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Radha Iyer answered |
Electric fuses are always connected in series with the live wire. Electric fuses are always connected in series with the live wire.
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