RC Circuits - Engineering

Q1:

A 12 k resistor is in series with a 0.02 F capacitor across a 1.2 kHz ac source. If the current is expressed in polar form as I = 0.30° mA, what is the source voltage expressed in polar form?

A 45.6 V

B 411.3 V

C 0.411 V

D 4.11 V

ANS:D - 4.11 V

Why we have to the square the resistance and capacitance values?