The circuit in the figure has a capacitor, C = 4.10 mF, connected to a V = 6.0-V

Question

The circuit in the figure has a capacitor, C = 4.10 mF, connected to a V = 6.0-V battery, two switches, and three resistors (R1 = 310 ?, R2 = 210 ?, and R3 = 120 ?. Initially, the capacitor is uncharged and both of the switches are open.

a) Switch S1 is closed. What is the current flowing out of the battery immediately after switch S1 is closed?

b) After 10.0 min, switch S2is closed. What is the current flowing out of the battery immediately after switch S2has been closed?

c) What is the current flowing out of the battery 10.0 min after switch S2has been closed?

d) After another 10.0 min, switch S1is opened. How long will it take until the current in theR2= 210-? resistor is below 1.00 mA?

Answers:

a)1.395?10-2A

b)1.553?10-2A

c)1.395?10-2A

d) I can't find , please help me :))

Explanation / Answer

d) We have a RC circuit: R = R2 + R3 = 210 + 120 = 330 ohms C = 4.10e-3 F i(t) = (Q/RC) e^(-t/(RC)) Q = C V' = C (i R3) = 4.10e-3*(1.395e-2)*(120) = 0.0068634 C i(t) = (Q/RC) e^(-t/(RC)) 1e-3 = (0.0068634/(330*4.10e-3))*e^(-/(330*4.10e-3)) 0.1971326 = e^(-/(330*4.10e-3)) t = 2.197 s

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