# Revision problems

### Explanation of question 8

A coil of resistance 6 takes a current of 2A when connected across a 20V AC supply. The reactance of the coil will be

1. 4
2. 6
3. 8
4. 10

The answer is :- 3

First we must calculate the overall impedance, then the reactive component of this impedance.

By Ohm's law, the impedance Z = V / I = 20 / 2 = 10

Impedance therefore

reactance

XL = 8

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