First slide

Electrostatic potential energy

Question

Three charges $Q, + q$ and $+ q$ are placed at the vertices of a right-angled isosceles triangle as shown. The net electrostatic energy of the configuration is zero if $Q$ is equal to

Moderate

A

$\frac{- q}{1 + \sqrt{2}}$
B

$\frac{- 2 q}{2 + \sqrt{2}}$
C

$- 2 q$
D

$+ q$

Solution

Net electrostatic energy $U = \frac{k Q q}{a} + \frac{k q^{2}}{a} + \frac{k Q q}{a \sqrt{2}} = 0$
$\Rightarrow \frac{k q}{a} (Q + q + \frac{Q}{\sqrt{2}}) = 0 \Rightarrow Q = - \frac{2 q}{2 + \sqrt{2}}$

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