Question

A 20 volts ac is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V, the voltage across the coil is

• A. 16 volts
• B. 10 volts
• C. 8 volts
• D. 6 volts

Answer 1

Answer: (A)

16 volts

Answer 2

The voltage across a L–R combination is given by

$V^{2} = V_{R}^{2} + V_{L}^{2}$

$V_{L} = \sqrt{V^{2} - V_{R}^{2}} = \sqrt{400 - 144} = \sqrt{256} = 16volt.$