Question

Three particles, each having a charge of $10\mu C$ are placed at the corners of an equilateral triangle of side $10cm$. The electrostatic potential energy of the system is (Given $\frac{1}{4\pi\varepsilon_{0}} = 9 \times 10^{9}N - m^{2}/C^{2}$)

• A. Zero
• B. Infinit
• C. $27J$
• D. $100J$

Answer 1

Answer: (C)

$27J$

Answer 2

For pair of charge

$U = \frac{1}{4\pi\varepsilon_{0}}.\frac{q_{1}q_{2}}{r}$ $U_{System} = \frac{1}{4\pi\varepsilon_{0}}\left\lbrack \frac{10 \times 10^{- 6} \times 10 \times 10^{- 6}}{10/100} \right.\$

$\left. \ + \frac{10 \times 10^{- 6} \times 10 \times 10^{- 6}}{10/100} + \frac{10 \times 10^{- 6} \times 10 \times 10^{- 6}}{10/100} \right\rbrack$

$= 3 \times 9 \times 10^{9} \times \frac{100 \times 10^{- 12} \times 100}{10} = 27J$