Concept #1: LR Circuits

Example #1: Unknown Resistance in an LR Circuit

Practice: Consider the LR circuit shown below. Initially, both switches are open. Switch 1 is closed. a) What is the maximum current in the circuit after a long time? Then, S1 is opened and S2 is closed. b) What is the current in the circuit after 0.05s?

Practice: An LR circuit with L = 0.1 H and R = 10 Ω are connected to a battery with the circuit initially broken. When the circuit is closed, how much time passes until the current reaches half of its maximum value?

An inductor with an inductance of L = 6.0 H and a resistor with resistance R = 10 Ω are connected in series to the terminals of a battery with EMF = 20 V and negligible internal resistance. There is a switch inserted in the circuit in line between battery and the inductor: Find the current 0.015 seconds after the switch is closed.

Consider the circuit shown in the sketch. The battery emf is 48.0 V, R1 = 16.0 Ω, and R2 = 6.00 Ω. Initially no currents are flowing. Then the switch is closed. After the switch has been closed a long time, what is the voltage vab across the inductor?

Consider the circuit shown in the sketch. Initially the switch is open and no currents flow.
After the switch has been closed a long time, it is opened. Just after the switch is reopened, what are the currents I1 and I2 through each resistor?

Consider the circuit shown in the sketch. The switch has been closed for a long time and then it is opened. Just after the switch is opened, the current in the 8.0 Ω resistor is
(a) zero
(b) 2.40 A
(c) 4.00 A
(d) 6.00 A
(e) none of the above answers

In the following circuit, the battery has a voltage of 40 V. At some instant in time, the voltage across the resistor is found to be 10 V. At this instant, what is the rate of change of current with respect to time?
A. 5 A/s
B. 10 A/s
C. 15 A/s
D. 20 A/s
E. 25 A/s