286
6 Oscillations
6.66 E(t) = E 0 e
−t/t c
∴
E(t 1/2 )
E 0
=
1
2
= e
−t 1/2 /t c
or t 1/2 = t c ln 2
6.67 A(t) = A 0 e
−t/2t c
A(t)
A 0
=
1
e
If t = 2t c = 8T
∴ t c = 4T
Q = 2π
t c
T
= 2π × 4 = 25.1