Question

A 460-loop circular armature coil with a diameter of 9.0 cm rotates at 120 rev/s in a uniform magnetic field of strength 0.60 T .

Part A

What is the rms voltage output of the generator?

Express your answer to two significant figures and include the appropriate units.

Part B

What would you do to the rotation frequency in order to double the rms voltage output?

What would you do to the rotation frequency in order to double the rms voltage output?

To double the output voltage, you must double the rotation frequency.

To double the output voltage, you must treble the rotation frequency.

To double the output voltage, you must decrease by two times the rotation frequency.

To double the output voltage, you must increase by four times the rotation frequency.

Answer 1

Given

No. of turns N=460

Diammeter of the coil D=0.09 m

frequency of rotation omega=120 rev/s

Magnetic Field B=0.6 T

According to Farday's Law, the induced emf is proportional to the rate of change of magnetic flux passing through the coil.

Thus,

(B)

Since from the above expression we see that the rms induced emf is directly proportional to the rotation frequency therefore to double the output rms voltage we have to double the rotation frequency.