Tag: physics

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

The working of magnetic braking of trains is based on

  1. Steady current

  2. Eddy current

  3. Alternating current

  4. Pulsating current
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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.

  1. True

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

Multiple choice physics household circuits electric switch switch electrical circuit

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

  1. potentiometer

  2. switch

  3. breaker

  4. fuse
Reveal answer Fill a bubble to check yourself
B Correct answer
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.
Multiple choice physics household circuits electric switch switch electrical circuit

The main function of a switch is to

  1. Allow changes of flow

  2. Complete or break a circuit

  3. Make the bulb glow easily

  4. Prevent electric shocks
Reveal answer Fill a bubble to check yourself
B Correct answer
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”).

Multiple choice physics household circuits electric switch switch electrical circuit

A switch is always connected to the :

  1. Live wire

  2. Neutral wire

  3. Earth wire

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice physics household circuits electric switch switch electrical circuit

Why are switches not connected to neutral wire?

  1. Because there will be overheating

  2. No current will flow through the appliance

  3. Fuse will blow

  4. All
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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