13.
(a) After the switch is thrown to position b the circuit is an LC circuit. The angular frequency of
oscillation is ω = 1/
√
LC. Consequently,
f =
ω
2π
=
1
2π
√
LC
=
1
2π
(54.0
× 10
−3
H)(6.20
× 10
−6
F)
= 275 Hz .
(b) When the switch is thrown, the capacitor is charged to V = 34.0V and the current is zero. Thus,
the maximum charge on the capacitor is Q = V C = (34.0V)(6.20
× 10
−6
F) = 2.11
× 10
−4
C. The
current amplitude is
I = ωQ = 2πf Q = 2π(275 Hz)(2.11
× 10
−4
C) = 0.365 A .