A real battery with internal resistance 0.460 Ω and emf 9.00 V is used to charge a 56.0-µF capacitor. A 21.0-Ω resistor is put in series with the battery and the capacitor when charging. (a) What is the time constant for this circuit?

Answer: 1.176*10^-3 s

Explanation: The time constant formulae for an RC circuit is given below as

t = RC

Where t = time constant, R = magnitude of resistance = 21 ohms, C = capacitance of capacitor = 56 uf = 56*10^-6 F

t = 56*10^-6 * 21

t = 1176*10^-6

t = 1.176*10^-3 s