Consider the circuit shown in the figure. w R 89 Ohms 9 Ohms a 90 b 9 Ohms 89 Ohms (a) Let the equivalent resistance of the circuit when the switch is open be Re the difference (in (2) between the two equivalent resistances, Re eq, open eq, open' R eq, closed and the equivalent resistance when the switch is closed be Re Find eq, closed" Req, open - Req, closed Ω (b) When the switch S is closed, the equivalent resistance drops to 58.0% of the original value. Determine the value of R (in 2). Ω

The switch is closed in Figure 18.20. After a long time compared with the time constant, of the circuit, what will the current be in the 2- resistor? (a) 4 A (b) 3 A (c) 2 A (d) 1 A (c) More information is needed. Figure 18.20 (Quick Quiz 18.9)

The switch S in Figure 20.27 is closed at t = 0 and the current at a reference time tref 0 is Iref. If the circuit is changed as, described below and the switch is again dosed at t = 0, determine whether the current I at the same time would be greater than, less than, or equal to the original value of Iref. Indicate your answers wilt G. L. or E, respectively. (a) Both the battery voltage and the resistance R are doubled. (b) The inductance L b doubled. (c) The battery voltage . the resistance R, and the inductance L are each doubled. Figure 20.27 A series RL circuit. As the current increases toward its maximum value, the inductor produces an emf that opposes the increasing current.

Check Your Understanding When using Kirchhoff’s laws, you need to decide which loops to use and the direction of current flow through each loop. In analyzing the circuit in Example 10.7, the direction of current flow was chosen to be clockwise, from point a to point b. How would the results change if the direction of the current was chosen to be counterclockwise, from point b to point a?