Question

When an inductor, a capacitor and a resistor are connected in series across a source of alterating emf, the potential difference across the inductor, capacitor and resistor are 70V, 30V and 30V respectively. Find the emf of the source

• A. 50V
• B. 60V
• C. 30V
• D. 80V

Answer 1

The correct option is A 50V

$V=\sqrt{V_R^2+[V_L-V_c{]}^2}$
$=\sqrt{{30}^2+[70-30{]}^2}$
$=\sqrt{{30}^2+{40}^2}=\sqrt{{50}^2}$
=50 V