First slide

Redistribution of charges and concept of common potential

Question

A $10 μ F$ capacitor is fully charged to a potential difference of 50V. After removing the source voltage it is connected to an uncharged capacitor in parallel. Now the potential difference across them becomes 20V. The capacitance of the second capacitor is:

Moderate

A

$15 μ F$
B

$10 μ F$
C

$30 μ F$
D

$20 μ F$

Solution

$V_{C M} (c o m m o n p o t e n t i a l) = \frac{C_{1} V_{1} + C_{2} V_{2}}{C_{1} + C_{2}}$
$\begin{array}{l} \Rightarrow 20 = \frac{10 \times 50}{10 + C_{2}} (∵ F o r u n c h a r g e d c a p a c i t o r, V = 0) \\ \Rightarrow 10 + C_{2} = 25 \\ \Rightarrow C_{2} = 15 μ F \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App