Tag: magnetic effects of electric current

Questions Related to magnetic effects of electric current

A device for producing electric current is ________.

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

  1. Ammeter

  2. Voltmeter

  3. Generator

  4. Galvanometer

Show answer
Correct Option: C
Explanation:

Generator is the device used for the production of electric current.

It works on the principle of Faraday's laws of Electromagnetic induction in which due to the change in the magnetic flux linked with the coil there is potential induced in the coil and since the circuit is closed the current flows throw the circuit.
Generator can be AC or DC type. It is an active device and acts as the source for current.

Which of the following statement is correct?

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

  1. AC generator generates a higher voltage

  2. DC generator generates a higher voltage

  3. AC generator has a permanent magnet whereas a DC generator has an electromagnet

  4. There is a split-ring commutator in a DC generator but not in an AC generator

Show answer
Correct Option: D
Explanation:

The voltage generated by a generator , whether AC or DC , depends upon the rate of change of flux linked with coil .

Both type of generators usually have permanent magnets .
There is a split- ring commutator in a DC generator but an AC generator has slip - rings .
Option D is correct .

The device which converts the mechanical energy in to electric energy is

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

  1. D.C. motor

  2. A.C. dynamo

  3. Transformer

  4. Starter

Show answer
Correct Option: B
Explanation:

The AC dynamo (generator) is made up of stationary magnets (stator) which create a powerful magnetic field, and a rotating magnet (rotor) which distorts and cuts through the magnetic lines of flux of the stator. When the rotor cuts through lines of magnetic flux it makes electricity. Thus mechanical energy is converted into electrical energy. 

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


An electric generator works on the principle of electromagnetic induction.

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

  1. True

  2. False

Show answer
Correct Option: A
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 $True$.

For a dynamo which one of the following statements is correct

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

  1. It converts electrical energy into light energy

  2. It converts kinetic energy into heat energy

  3. It converts mechanical energy into electrical energy

  4. It converts electrical energy into mechanical energy

Show answer
Correct Option: C
Explanation:

A  dynamo converts mechanical energy into electrical energy according to Faraday's Law of Electromagnetic Induction.


Answer-(C).

To convert mechanical energy into electrical energy, one can use

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

  1. DC dynamo

  2. AC dynamo

  3. motor

  4. (A) & (B)

Show answer
Correct Option: D
Explanation:

Dynamo is a device which converts mechanical energy into electrical energy.

Hence, both DC dynamo and AC dynamo can be used.

Hence, answer is option-(D)

The current produced in a generator armature is AC because

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

  1. the magnetic field reverses at intervals

  2. The current in the field coils is AC

  3. the rotation of the armature causes the field through it to reverse

  4. the commutator feeds current into it in opposite directions every half cycle

Show answer
Correct Option: C
Explanation:

After every half rotation, the direction of e.m.f reverses and hence current changes its direction after a regular interval.

Hence, Answer-(C)