In a model AC generator, a 505 turn rectangular coil 7.0 cm by 23 cm rotates at

Question

In a model AC generator, a 505 turn rectangular coil 7.0 cm by 23 cm rotates at 125 rev/min in a uniform magnetic field of 0.6 T.
(a) What is the maximum emf induced in the coil?
63.085V correct

(b) What is the instantaneous value of the emf in the coil at t = (?/40) s? Assume that the emf is zero at t = 0.
Incorrect: Your answer is incorrect.
Your response differs from the correct answer by more than 10%. Double check your calculations.
58V

(c) What is the smallest value of t for which the emf will have its maximum value?
.12s correct

I am within 10% of the correct value of B, but cannot figure it out. Please help, Thank you!

Explanation / Answer

= d/dt

=A*B*(d/dt)*sin

= A*B**sin

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= 2f = 2 * 3.14 * (125/60) = 13.0833

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max = N A B

       = 505 * (0.07)(0.23)(0.6)(2*125/60)

   = 63.824 V

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at t = /40 >>>> = t = 13.0833*(3.14/40) = 1.02703905 rad

(Note that 's dimention is rad (not degree))

= N*A*B**sin

   = 505*(0.07)(0.23)(0.6)(13.0833)(sin(1.02703905))

   = 54.641 V   (or 53.99 V)

------------------------------------------------------------------------------

T = 2/ = 0.48 s

emf is maximum >>> t = T/4 >>>> t = 0.12 s

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