L
τ=
R

Solution
(a)
L
τ=
R
10
=
60
= 0.17 seconds
(b)the time it will take to reach its final value is five time constants (5 τ)
5 x 0.17 = 0.85 seconds
(c)the approximate final magnitude of current after 0.85 seconds can be
calculated using ohmʼs law:
V
I=
R
120
=
60
=2A

63% of the difference
between the maximum
voltage and the current
voltage.

Maximum Circuit Current = 10 amps

Current = 63.2% = 6.32 amps
Max Voltage = 10 amps
10 - 6.32 = 3.68
The difference is 3.68 amps
63.2% of 3.68 = 2.32 amps

6.32 + 2.32 = 8.64 amps