Question

A capacitor is connected across an AC generator whose frequency is 31 Hz and has a peak voltage 124 V. The rms current in the circuit is 33 A. a) What is the capacitance of the capacitor? Cmax = __________ F b) What is the magnitude of the maximum charge on one plate of the capacitor? Qmax = __________ C

Answer 1

Sol: Information provided in the question:

The frequency (f) = 31 Hz

Peak voltage (Vp )= 124 V

RMS current in circuit (Irms ) = 33 A

(a) => Now the RMS Voltage =

=>

33 = ( 2x pix 31x C x 87.6812)

Capacitance (C) = 33 / ( 2x pix 31x 87.6812 ) = 1.93226 x 10^-3 F

Hence Cmax = 1.93226 x 10^-3 F

(b) The magnitude of the maximum charge on one plate of the capacitor

Q max = Vp x Cmax = 124 x  1.93226 x 10^-3

Qmax = = 124 x  1.93226 x 10^-3

Hence Qmax = = 0.239600 Coulomb (C)