SP 212 Worksheet
Lesson 28: Ch. 30.6, RL Circuits
Consider the following RL circuit.
1) After being left in position a for a very long time, the switch is flipped to position b at time t = 0. The
current drops from i = 1.2 A to i = 0.12 A in one second. If L = 14 H, what is R?
2) After being left in position b for a very long time, the switch is flipped to position a at time t = 0. At
what time t will the current be 0.9 times its asymptotic value? Express your answer in units of τL .
3) From last time: A 1300 turn solenoid is 1.2 m long and has a cross-sectional area of 18 cm2 . The solenoid
carries a current of 9.0 A. Calculate the self-inductance of this solenoid.