Tag: physics

Questions Related to physics

The working of magnetic braking of trains is based on

eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

  1. Steady current

  2. Eddy current

  3. Alternating current

  4. Pulsating current

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Correct Option: B
Explanation:

 It works the same as a disk eddy current brake, by inducing closed loops of eddy current in the conductive rail, which generate counter magnetic fields which oppose the motion of the train.

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

Eddy current involves loss of energy in the form of heat.

eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

  1. True

  2. False

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Correct Option: A
Explanation:

Eddy currents (also called Foucault currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor due to Faraday's law of induction. 

Eddy current involves loss of energy in the form of heat. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an AC electromagnet or transformer. 
The statement is true.

A device that is used to break or make an electric circuit is called _________.

physics household circuits electric switch switch electrical circuit

  1. potentiometer

  2. switch

  3. breaker

  4. fuse

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Correct Option: B
Explanation:
A 'switch' is an electric device that is used to make or break a circuit. When the switch is in 'OFF' position, then the circuit is not complete. Then, the circuit is called an Open circuit. An electric current cannot flow through the circuit. and vice versa.

The main function of a switch is to

physics household circuits electric switch switch electrical circuit

  1. Allow changes of flow

  2. Complete or break a circuit

  3. Make the bulb glow easily

  4. Prevent electric shocks

Show answer
Correct Option: B
Explanation:

An electrical switch is any device used to interrupt the flow of electrons in a circuit. Switches are essentially binary devices: they are either completely on (“closed”) or completely off (“open”).

A switch is always connected to the :

physics household circuits electric switch switch electrical circuit

  1. Live wire

  2. Neutral wire

  3. Earth wire

  4. None of these

Show answer
Correct Option: A
Explanation:

A switch is always connected to live wire. The purpose of the switch is to break or connect an electric circuit, but they must be correctly connected at home.

Why are switches not connected to neutral wire?

physics household circuits electric switch switch electrical circuit

  1. Because there will be overheating

  2. No current will flow through the appliance

  3. Fuse will blow

  4. All

Show answer
Correct Option: A
Explanation:

If the switches are connected to neutral wire, no current will flow through the appliance and hence it will not operate.

Commonly used switches are 

physics household circuits electric switch switch electrical circuit

  1. Clutch type

  2. Lever type

  3. Plug type

  4. All of the above

Show answer
Correct Option: B
Explanation:

Commonly used switches are lever type. By moving the lines upward, a given circuit is switched off and vice-versa.

Switches are connected to

physics household circuits electric switch switch electrical circuit

  1. Live wire

  2. Neutral wire

  3. Fuse wire

  4. All of the above

Show answer
Correct Option: A
Explanation:

When an appliance is in contact with the live wire, its heating element will be at same potential as the live wire and current will flow.

MCB are

physics household circuits electric switch switch electrical circuit

  1. Miniature circuit Breakers

  2. Switches

  3. Pulg

  4. Fuse

Show answer
Correct Option: A
Explanation:

MCB stands for Miniature circuit breakers which opens the circuit when excessive current passes through the appliance and thus prevents the appliance from any damage.

The switch used with an appliance to start or stop the flow of current in it is the

physics household circuits electric switch switch electrical circuit

  1. Double pole switch

  2. Single pole swicth

  3. MCB

  4. All

Show answer
Correct Option: B
Explanation:

Single pole switch is used with an appliance to start or stop the flow of current in it.