A.C. GENERATOR

In A.C generator,by increasing the no. of turns in the coil,

• Decrease the Electromotive force (EMF)

• Electromotive force (EMF) remains the same

• Increases the Electromotive force (EMF)

• Electromotive force (EMF) becomes zero

If the coil is placed perpendicular to field lines then the number of lines passing through the coil is:

• Minimum

• Maximum

• Zero

• May be maximum or minimum

AC generator converts:

• Mechanical energy to electrical energy

• Electrical energy to mechanical energy

• Heat energy to mechanical energy

• Chemical energy to electrical energy

The direction of induced emf or current is indicated by:

• Fleming’s left-hand rule

• Fleming’s right-hand rule

• Faraday’s law of electromagnetic induction

• Ampere’s swimming rule

In an a.c. generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency ω in a magnetic field B the maximum value of emf generated in the coil is:

• NABR

• NABω

• NABRω

• NAB

When a coil is held stationary in magnetic field, the induced current in it:

• continuously changes

• randomly changes

• remains zero

• becomes maximum

What is true of AC GENERATOR?

• It works on the principle of electromagnetic induction

• The mechanical energy of the rotation is converted into electrical energy

• A pair of slip rings are used in the AC generator

• All the above

What determines the frequency of a.c. produced by a generator?

• Speed of rotation of coil

• The number of rotations of coil in one-second

• Both speed of rotation and number of rotation of coil in one-second

• None of these

What does the index finger show you in the Fleming’s right-hand rule?

• Direction of current

• Motion of wire

• Direction of electric field

• Direction of magnetic field

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NGSS.HS-PS2-5

NGSS.HS-PS3-5

The Fleming's right-hand rule is used when ....

• motion causes current

• current causes motion

• current causes potential difference

• motion causes magnetic field