Question

A R = 711 Ω resistor, an uncharged C = 185 μF capacitor, and a ε = 6.64 V emf are connected in series.

A) What is the initial current in amps?

B) What is the RC time constant in seconds?

C) What is the current after one time constant in amps?

D) What is the voltage on the capacitor after one time constant in volts?

Answer 1

711 2 185MF E = 6,64V initially capacitor is uncharged it behaves as a short circuit and this time current is maximum in the circuit which is given by io = 10 = 6.64 = 0.00934A 10 = 9.34 x 10-3 A RC time constant T= RC T(711) X (185 x 10- 0.132s current in the circuit as a function of time is given by i =ine- at 1=lt i = ige-1 i = i = 9.34 x 10-3 i = 3.436 x 10-3 A

the current after one time constant 3.436 x 10-3 A voltage on the resistor after one time constant is Vr =iR Vr = (3.436 x 10-3)x (711) VR = 2.443V Now the voltage on the capacitor after one time constant is Vi = £ - VR V. = 6.64 – 2.443 V. = 4.197V