84.
(a) The magnitude of the average induced emf is
E
avg
=
−dΦ
B
dt
∆Φ
∆t
BA
i
t
(2.0 T)(0.20 m)
2
0.20 s
−0.40 V .
(b) The average induced current is
R
0.40 V
20
× 10
−3
Ω
= 20 A .