Tag: eddy currents

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Questions Related to eddy currents

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

Identify the wrong statement

  1. Eddy currents are produced in a steady magnetic field

  2. Eddy currents can be minimized by using laminated core

  3. Induction furnace uses eddy current to produce heat

  4. Eddy current can be used to produce breaking force in moving trains
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eddy currents comes in picture only when there is change in linked magnetic flux. 

They can be created when a conductor is moving through a magnetic field, or when the magnetic field surrounding a stationary conductor is varying i.e. anything which results in the conductor experiencing a change in the intensity or direction of a magnetic field can produce eddy currents.

Thus  $A$ is the correct option.

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

Identify the wrong statement.

  1. Eddy currents are produced in a steady magnetic field.

  2. Eddy currents can be minimized by using laminated core.

  3. Induction furnace uses eddy current to produce heat.

  4. Eddy current can be used to produce breaking force in moving trains.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eddy currents comes in picture only when there is change in linked magnetic flux. Thus statement A is wrong.

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

Which of the following law follows when eddy currents are generated?

  1. Lenz's law

  2. Gauss's law

  3. Both A and B

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

Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field.By Lenz's law, an eddy current creates a magnetic field that opposes the change in the magnetic field that created it, and thus eddy currents react back on the source of the magnetic field.Lenz law, the current swirls in such a way as to create a magnetic field opposing the change; for this to occur in a conductor, electrons swirl in a plane perpendicular to the magnetic field.

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

Which of the following is true in context of Eddy currents?

  1. By Lenz's law, an eddy current creates a magnetic field that opposes the magnetic field that created it.

  2. Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction

  3. Eddy currents are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators etc.

  4. All of the above

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction,are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators etc.

By Lenz's law, an eddy current creates a magnetic field that opposes the magnetic field that created it.
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Multiple choice eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

Eddy currents travel in

  1. closed paths.

  2. nonconductive materials.

  3. axially when testing rod with an encircling coil

  4. perpendicular to the test surface
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When there is a change in magnetic flux associated with a large piece of metal then currents are induced in that metal these currents are travelling in a closed circular path,  similar to Whirlpools or eddies in water. Such currents are known and Eddy Currents

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

Hysteresis loss and eddy current losses are used in

  1. induction heating of steel

  2. dielectric heating

  3. induction heating of brass

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

There is a magnetic loss occur in ferromagnetic material like iron and steel in form of heat these losses are used for induction heating and cooking. For example $\rightarrow$ heating of transformer.

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

Which of the following is not an application of eddy currents.

  1. Induction heater

  2. Conductivity meters for non-magnetic metals

  3. Skin effect

  4. Coating Thickness Measurements
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Eddy currents are the currents induced in the body of a conductor when the amount of magnetic   flux linked with it changes
(i)    Induction furnace (heating effect of eddy current)
(ii)   Dead-beat galvanometer (electromagnetic damping)
(iii)  Electric brakes
(iv) Diathermy ( Strong 50 MHz A.C. passed through human body, also called deep heat treatment )
(v)  Induction motor
(vi) Car-speedometer
(vii)Energy meter
Multiple choice eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

Silicon steel used in lamination mainly reduces

  1. Hysteresis loss

  2. Eddy current losses

  3. Copper loss

  4. All of the above

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Silicon steel used in lamination mainly reducesHysteresis loss,Eddy current losses,Copper loss. In order to minimize the eddy currents more,magnetic core is laminated . The hysteresis coefficient of silicon steel is less, so hysteresis loss can be reduced. used mainly because of the following advantages: low hysteresis loss. low copper loss due to lower grain resistance.