35.
In a model ac generator, a 500turn rectangular coil, 8.0 cm by 20 cm, rotates
at 120 rev/min in a uniform magnetic field of 0.60 T. (a) What is the maximum emf
induced in the coil? (b) What is the instantaneous value of the emf in the coil at
t
= (
π
/32) s? Assume that the emf is zero at
t
=
0
. (c) What is the smallest value of
t
for which the emf will have its maximum value?
Solution
When a coil rotates in a uniform magnetic field, the emf induced in that coil is
given by
E
=
(
)
NBA
t
ω
ω
sin
.
Here,
N
is the number of turns on the coil,
B
is the
magnitude of the magnetic field,
A
is the area enclosed by the coil, and
ω
is the
angular frequency of the coil.
(a)
The angular frequency of the coil is
ω
π
π
=
=
120
2
1
4
rev
min
rad
1 rev
min
60 s
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 Spring '10
 Avram
 Physics, Frequency, Magnetic Field, 8.0 cm, 1 min, 0.20 m, 0.080 M

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