Question

Eight charges having the valves as shown are arranged symmetrically on a circle of radius 0.4m in air. Potential at centre O will be

• A. $63 \times 10^{4}volt$
• B. $63 \times 10^{10}volt$
• C. $63 \times 10^{6}volt$
• D. Zero

Answer 1

Answer: (A)

$63 \times 10^{4}volt$

Answer 2

Due to the principle of superposition potential at O

$\mathbf{V =}\frac{\mathbf{1}}{\mathbf{4\pi}\mathbf{\varepsilon}_{\mathbf{0}}}\mathbf{\times}\frac{\mathbf{28}\mathbf{\times}\mathbf{1}\mathbf{0}^{\mathbf{-}\mathbf{6}}}{\mathbf{0.4}}\mathbf{= 9}\mathbf{\times}\mathbf{1}\mathbf{0}^{\mathbf{9}}\mathbf{\times}\frac{\mathbf{28}\mathbf{\times}\mathbf{1}\mathbf{0}^{\mathbf{-}\mathbf{6}}}{\mathbf{0.4}}\mathbf{= 63}\mathbf{\times}\mathbf{1}\mathbf{0}^{\mathbf{4}}\mathbf{volt}$