Currentin a RL Circuit The equation governing the amount of currentI(in amperes) after time t(in
seconds) in a simple RL circuit consisting of a resistance R(in ohms), an inductance L (in henrys), and
an electromotive force E (in volts) is
[1 ]
(R/ L)t
e
R
E
I
−
= −
If E = 12 volts, R = 10 ohms, and L = 5 henrys, how long does it take to obtain a current of 0.5 ampere?
Of 1.0 ampere?

Question

Currentin a RL Circuit The equation governing the amount of currentI(in amperes) after time t(in 
seconds) in a simple RL circuit consisting of a resistance R(in ohms), an inductance L (in henrys), and 
an electromotive force E (in volts) is
[1 ]
(R/ L)t
e
R
E
I
−
= −
If E = 12 volts, R = 10 ohms, and L = 5 henrys, how long does it take to obtain a current of 0.5 ampere? 
Of 1.0 ampere?

radar · Answer

This boils down to this equation:$$.5 =1.2(1-e ^{-2t})$$Solve for t.
for the second part use same equation but substitute 1.0 for the .5