All questions in this section must be worked. One of the questions will be grade

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All questions in this section must be worked. One of the questions will be graded. Open-Response Homework Problem 9.1 For the figure to the right with R_1 = 100Omega, R_2 = 200Omega, deltaV_0 = 10V, and C = 1000MewF. Initially, S_1 is open and the capacitor is uncharged. Immediately after S_1 is closed, what is the current through R_1? What is the current as a function of time, if Si is closed at time to = 0? Define and give values for any constants you introduce. After S_1 has been closed for a long time, what is the current through R_1? After S_1 has been closed for a long time, S_1 is opened and S_2 is closed. What is the current through Ro immediately after S_2 is closed? What is the current as a function of time, if S_2 is closed at time t_0 = 0? Open-Response Homework Problem 9.2 Consider the circuit below. All batteries have potential difference deltaV_batt. Use R_1, R_2, etc. for the resistances. Use the current direactions drawn. List any series or parallel combinations of resistors. State whether the combinations you list are series or parallel combinations. Write a loop equation for loop 1 (ABCA). Write a loop equation for loop 2 (DACD). Write a junction equation for junction A.

Explanation / Answer

a) I= V/R = 10/100 = 0.1 A

b) I(t) = (Qo/RC) e-t/ = (V/R)e-t/

c) put t= infinity in above eqn

I(infinity) = (Qo/RC) e-t/ = Io e-infinity/ = 0 A

d) I(t) = -(Qo/RC) e-t/ = -Io e-t/ = -(V/R)e-t/

plug t=0s and R=200 ohm in above eqn

I(t) = -(10/200)e-0/ = 0.95A

I(t) = -(Qo/RC) e-t/ = -Io e-t/ = -(V/R)e-t/

put t= infinity in above eqn

I(t) = -(10/200)e-infinity/ = 0 A

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