# Simple alternating current circuits

### Explanation of question 14

A 20 F Capacitor is connected across an 8V, 1kHz supply. The current taken will be approximately

1. 0.5A
2. 1A
3. 1.5A
4. 2A

The answer is :- 2 First we must calculate the reactance (ac resistance) of the capacitor, then calculate the current by Ohm's Law.

Taking an approximation of 2xPI as 6.28

Xc = 1 ÷ (6.28 x FREQ x CAP)

= 1 ÷ (6.28 x 1000 x 0.00002) = 1 ÷ 0.1256 = approximately 8 ohms

I = V / R = 8 / 8 = 1A

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