Question

Electric charges of $+ 10\mu C,\mspace{6mu} + 5\mu C,\mspace{6mu} - 3\mu C$ and $+ 8\mu C$ are placed at the corners of a square of side $\sqrt{2}$m. the potential at the centre of the square is

• A. 1.8 V
• B. $1.8 \times 10^{6}$ V
• C. $1.8 \times 10^{5}$V
• D. $1.8 \times 10^{4}$V

Answer 1

Answer: (C)

$1.8 \times 10^{5}$V

Answer 2

Length of each side of square is $\sqrt{2}m$ so distance of it’s centre from each corner is $\frac{\sqrt{2}}{\sqrt{2}} = 1m.$

Potential at the centre

$V = 9 \times 10^{9}\left\lbrack \frac{10 \times 10^{- 6}}{1} + \frac{5 \times 10^{- 6}}{1} - \frac{3 \times 10^{- 6}}{1} + \frac{8 \times 10^{- 6}}{1} \right\rbrack$ = 1.8 × 10⁵ V