Tag: physics

Questions Related to physics

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

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

  1. strength of magnetic field increases.

  2. current produced will be increased.

  3. voltage produced will be increased.

  4. all

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Correct Option: D
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.

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

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

  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.

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Correct Option: C
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.

A commutator changes the direction of current in the coil of

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

  1. a DC motor

  2. a DC motor and an AC generator

  3. a DC motor and a DC generator

  4. an Ac generator

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Correct Option: C
Explanation:

The only difference between a DC generator and an AC generator is in the way the two ends of the generator coil are linked to the outer circuit.

What is a commutator?

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

  1. A device that reverses the direction of flow of current through a circuit is called a commutator.

  2. A device that flows in the direction of flow of current through a circuit is called a commutator.

  3. A device that reverses the direction of flow of voltage through a circuit is called a commutator.

  4. All

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Correct Option: A
Explanation:

A device that reverses the direction of flow of current through a circuit is called a commutator. In electric motors, the split ring acts as a commutator.

AC generator is also h/a

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

  1. convertor

  2. invertor

  3. alternator

  4. none

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Correct Option: C
Explanation:

AC generator produces alterating current which reverses its direction continuously. It is also h/a alternator.

Electric generator is classified on the bases of

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

  1. peak of electric voltage produced.

  2. type of electric current produced.

  3. power produced.

  4. none

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Correct Option: B
Explanation:

An electric generator is classified on the basis of type of electric current it produces

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

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

  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.

Show answer
Correct Option: D
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.

Dynamo is a type of

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

  1. Electrical generator

  2. Electrical motor

  3. Mechanical generator

  4. Mechanical motor

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Correct Option: A
Explanation:

Dynamo is a type of electrical generator and produces dc current as output.

A dynamo consists of

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

  1. a horse-shoe magnet

  2. an armature coil

  3. two slip rings

  4. all of these

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Correct Option: D
Explanation:

A dynamo consists of 
1) A horse-shoe magnet 
2) An armature coil 
3) Two slip rings
4) Two carbon brushes
5) The external circuit (or load)

A dynamo does not consist of

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

  1. a bar magnet

  2. two carbon brushes

  3. the external circuit

  4. all of these

Show answer
Correct Option: A
Explanation:

A dynamo consists of 
1) A horse-shoe magnet 
2) An armature coil  
3) Two slip rings
4) Two carbon brushes
5) The external circuit (or load)

It does not consist of a bar magnet.