Question

A $50\, Hz$ AC source of $20$ volts is connected across $R$ and $C$ as shown in figure. The voltage across $R$ is $12$ volt. The voltage across $C$ is

• A. 8 V
• B. 16 V
• C. 10 V
• D. not possible to determine unless values of R and C are given

Answer 1

Answer: (B)

16 V

Answer 2

Voltage across capacitor lags behind current by $90^{\circ}$. The given circuit is a $C-R$ series circuit, $V_{R}$ is in phase with $i$, while $V_{C}$ lags behind $i$ by $90^{\circ}$. Hence, resultant potential is