A generator is constructed by rotating a coil of N turns in a magnetic field B a

Question

A generator is constructed by rotating a coil of N turns in a magnetic field B at a frequency f. The internal resistance of the coil is R and the cross sectional area of the coil is A. Decide which statements are true and which are false. If the first is T and the rest F, enter TFFFFF.

A) The maximum induced EMF doubles if the frequency f is doubled.

B) The maximum induced EMF doubles if the magnetic field B is doubled.

C) The maximum induced EMF occurs when the coil is rotated about an axis parallel to the magnetic field lines.

D) The maximum induced EMF doubles if the resistance R is doubled.

E) The maximum induced EMF doubles if the area A is doubled.

F) The maximum induced EMF occurs when the coil is rotated about an axis normal to the plane of the coil.

Explanation / Answer

A) The maximum induced EMF doubles if the frequency f is doubled.

TRUE.

Emax=N*2*pi*f*flux (max)

so if you double the frequency then max. EMF is doubled.

B) The maximum induced EMF doubles if the magnetic field B is doubled.

TRUE.

E=-NA*dB/dt.

so if you double the B then max. EMF is doubled.

C) The maximum induced EMF occurs when the coil is rotated about an axis parallel to the magnetic field lines.

FALSE.

When the coil rotates perpendicular to the magnetic field lines only , EMF will be maximum.

D) The maximum induced EMF doubles if the resistance R is doubled.

FALSE.

induced emf has nothing to do with R .

E) The maximum induced EMF doubles if the area A is doubled.

TRUE.

E=-NA*dB/dt.

so if you double the A then max. EMF is doubled.

F) The maximum induced EMF occurs when the coil is rotated about an axis normal to the plane of the coil.

TRUE.

When the coil rotates perpendicular to the magnetic field lines only , EMF will be maximum.

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