Question

Three particles, each of charge $10\mu C$ are placed at the corners of an equilateral triangle of side 10 cm. The electrostatic potential energy of the system is
Given$(\frac{1}{4\pi ϵ}=9\times {10}^{9}N-m^2/C^2)$

• A. Zero
• B. Infinite
• C. 27 J
• D. 100 J

Answer 1

The correct option is C 27 J

For pair of charge $U=\frac{1}{4\pi {ϵ}_0}[\frac{10\times {10}^{-6}\times 10\times {10}^{-6}}{\frac{10}{100}}+\frac{10\times {10}^{-6}\times 10\times {10}^{-6}}{\frac{10}{100}}+\frac{10\times {10}^{-6}\times 10\times {10}^{-6}}{\frac{10}{100}}]$
$=3\times 9\times {10}^9\times \frac{100\times {10}^{-12}\times 100}{10}=27J$