First slide

Potential energy

Question

An isolated copper sphere is charged and the electrostatic energy stored in it is 16µJ. An internal agent supplies some charge in the sphere so that its charge becomes doubled, then work done by the external agent is

Moderate

A

24 µJ
B

32 µJ
C

48 µJ
D

36 µJ

Solution

If initial charge on the sphere is Q,
then $U_{i} = \frac{Q^{2}}{2 \times 4 π \in_{o} R}$ where R = radius.
Now, $U_{f} = \frac{{(2 Q)}^{2}}{2 \times 4 π \in_{o} R} = 4 U_{i}$
$∴ W = U_{f} - U_{i} = 4 U_{i} - U_{i} = 3 U_{i} = 3 \times 16 μJ = 48 μJ$

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