SP 212 Worksheet
Ch. 27.4, RC circuits
In this circuit, E = 12.0 V, R = 1.40 MΩ, and C = 1.80 µF.
1) Suppose the capacitor is uncharged at time t = 0, and the switch is thrown to position a.
a) Calculate the time constant τ .
b) What is the maximum charge that will build on the capacitor?
c) How long does it take for the charge on the capacitor to reach 95% of its maximum value?
d) How much energy is stored in the capacitor at t = 5 s?
2) Suppose the capacitor is completely charged at time t = 0, and the switch is thrown to position b.
a) How long does it take for the capacitor to lose 2/3 of its initial charge?
b) When the capacitor has lost 2/3 of its charge, what is the current in the circuit?
c) Challenge: By the time the capacitor is completely discharged, how much energy has been dissipated by
the resistor?