Question

Three charges \( Q, -2q \) and \( -2q \) are placed at the vertices of an isosceles right-angled triangle as shown in figure. The net electrostatic potential energy is zero if \( Q \) is equal to

• A. \( \frac{q}{2} \)
• B. \( \sqrt{2}\,q \)
• C. \( \frac{q}{\sqrt{2}} \)
• D. \( \frac{q}{2\sqrt{2}} \)

Hint:

- Always sum pairwise energies - Use geometry carefully (hypotenuse = $\sqrt{2}l$)

Answer 1

The Correct Option is C