Question

In $R-L-C$ series circuit, the potential differences across each element is $20\,V$. Now the value of the resistance alone is doubled, then $P.D.$ across $R, L$ and $C$ respectively

• A. 20 V, 10 V, 10 V
• B. 20 V, 20 V, 20 V
• C. 20 V, 40 V, 40 V
• D. 10 V, 20 V, 20 V

Answer 1

Answer: (A)

Given, the potential difference across each element is same i.e., $20 \,V , so$, the circuit is at resonance and we have
$V=V_{R}=20\, V$
If the value of $R$ is doubled, then value of $/$ reduced to half
$\therefore V_{L}=V_{C}=\frac{I X_{L }}{2}=\frac{I X_{C}}{2}=\frac{20}{2}=10\, V$
$(\because$ circuit is at resonance $) $
and $V_{R}=V=20\, V$