Physics

Magnetism and Electromagnetism

1,019 Questions

This hub provides practice questions on magnetism and electromagnetism. It covers magnetic flux density, electromagnets, magnetic lines of force, and electromagnetic induction. These physics concepts frequently appear in technical and non-technical competitive exams.

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Magnetism and Electromagnetism Questions

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

A small AC dynamo is connected to a galvanometer and gently rotated, then the needle of the galvanometer,

  1. Moves toward left.

  2. Moves towards right.

  3. Remains in the same position.

  4. Moves towards both right and left.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A small AC dynamo is connected to a galvanometer and gently rotated, then the needle of the galvanometer moves towards both right and left The deflection of the needle of a galvanometer indicates a current flowing through the small stator winding (wound coil) inside the device. The more current flowing through the coil the greater the magnetic disturbance 

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

The essential difference between a d.c. dynamo and an a.c. dynamo is that

  1. a.c. has an electromagnet but d.c. has a

    permanent magnet

  2. a.c. will generate a higher voltage

  3. a.c.has slip rings but the d.c. has a commutator

  4. a.c. dynamo hyas a coil wound on soft iron,

    but the d.c. dynamo has a coil wound on copper
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The a.c dynamo has step rings because it changes polarity in every half cycle.

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

If the coil in a simple generator is wound around a soft iron core then:

  1. strength of magnetic field increases.

  2. current produced will be increased.

  3. voltage produced will be increased.

  4. all
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Voltage/current produced in a generator can be increased by: 
a) Using a powerful electromagnet to make the magnetic field stronger in place of a permanent magnet.
b) By winding the coil round a soft iron core to increase the strength of magnetic field.
c) By using a coil with more turns.
d) By rotating the coil faster.
e) By using a coil with a larger area.

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

If we use a powerful electromagnet in place of permanent magnet in a generator, then:

  1. voltage produced by the generator increases.

  2. current produced by the generator increases.

  3. Both A and B are true.

  4. No effect on current or voltage occurs.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If a powerful electromagnet is used instead of a permanent magnet, magnetic field strength increases. This increase in magnetic field strength leads to the increase in induced voltage in the coil. An increased voltage leads to an increased induced current in the generator.

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

Which of the following can't increase the voltage produced by the generator?

  1. Using a powerful electromagnet to make the magnetic field stronger in place of a permanent magnet.

  2. By winding the coil round a soft iron core to increase the strength of magnetic field.

  3. By using a coil with more turns.

  4. Changing the material of the coil.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Voltage/current produced in a generator can be increased by:
a) Using a powerful electromagnet to make the magnetic field stronger in place of a permanent magnet.
b) By winding the coil round a soft iron core to increase the strength of magnetic field.
c) By using a coil with more turns.
d) By rotating the coil faster.
e) By using a coil with a larger area.

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

Generators uses the principle of ________ to push electrons through a wire.

  1. electromagnetic induction

  2. electromagnetic reduction

  3. magnetoelectric conduction

  4. electric induction

  5. magnetic field contraction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The EMF generated by Faraday's law of induction due to relative movement of a circuit and a magnetic field is the phenomenon underlying electrical generators. When a permanent magnet is moved relative to a conductor, or vice versa, an electromotive force is created. If the wire is connected through an electrical load, current will flow, and thus electrical energy is generated, converting the mechanical energy of motion to electrical energy.

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

Read the following statements and answer whether the given statement is true or false.


An electric generator works on the principle of electromagnetic induction.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An electric generator works on the principle of Electromagnetic Induction.

In it, an e.m.f is induced in the coil when the magnetic flux linked with the coil changes.

Hence, the given statement is $True$.