Tag: motional emf

Questions Related to motional emf

Eddy currents are used in

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

  1. electrolysis

  2. making a galvanometer dead beat

  3. electroplating

  4. to increase the sensitivity of galvanometer

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Correct Option: B
Explanation:

In general the coil of galvanometer oscillates about it's equilibrium due to rotational inertia which consumes some time. To avoid this coils is bound over  a metallic frame or plate oscillates in a magnetic field the eddy currents generated in the frame or plate oppose the motion and bring the frame to rest as the oscillations die out quickly. This is known as making galvanometer dead beat. 

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.