Question

An uncharged 3.0-μF capacitor is connected in series with a 30-kΩ resistor, an ideal 6.7-V battery, and an open switch. What is the voltage across the capacitor 21 ms after closing the switch?

15.2 V

6.70 V

12.0 V

1.39 V

Answer 1

The charging of a capacitor connected to a series RC circuit depends on the time constant () of the RC circuit.

where,

Hence the charging equation for a capacitor connected in a circuit is given by,

  

where,

V0 = Supply Voltage = 6.7V

t = 21ms = 0.021s

R = 30k = 30x103

C = 3F = 3x10-6 F

  

= 1.39 V (Ans.)