Question

Example 7.4 A 15.0 pF capacitor is connected to a 220 V, 50 Hz source
Find the capacitive reactance and the current (rms and peak) in the
circuit. If the frequency is doubled, what happens to the capacitive
reactance and the current?​

Answer 1

Answer:

Given : C=15×10^-6 F

Rms value of voltage Vrms=220 V

220 VFrequency of source f=50 Hz

HzCapacitive reactance Xc=1/2πfC

=1/2π×50×15×10^-6

= 212.3Ω

Rms value of current Irms=Vrms/Xc

=220/212.3

=1.04 A

Peak value of current Io=√2Irms

=√2×1.04=1.465 A

Since Xc ∝ 1/f

So capacitive reactance gets halved if the frequency is doubled.

Also, Irms ∝ 1/Xc ∝ f

So current becomes doubled if the frequency is doubled.