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

The correct option is A 16 volts

The voltage across a L-R combination is given by
$V^2=V_R^2+V_L^2$
$V_L=\sqrt{V^2-V_R^2}=\sqrt{400-144}=\sqrt{256}=16volt$.