Question

Three charges ${{Q}_{0}},-q$ and $-q$ are placed at the vertices of an isosceles right angle triangle as in the figure. The net electrostatic potential energy is zero if ${{Q}_{0}}$ is equal to

• A. $\frac{q}{4}$
• B. $\frac{2q}{\sqrt{32}}$
• C. $\sqrt{2q}$
• D. $+q$

Answer 1

Answer: (B)

$\frac{2q}{\sqrt{32}}$

Answer 2

Here total electrostatic potential energy is zero ie, $\frac{-{{Q}_{0}}q}{l}-\frac{q{{Q}_{0}}}{l}+\frac{{{q}^{2}}}{\sqrt{2}l}=0$ On solving, ${{Q}_{0}}=\frac{q}{2\sqrt{2}}=\frac{2q}{\sqrt{32}}$