Question

Work done by an external agent to move slowly a charge Q from rim of a uniformly charged horizontal disc of radius a and charge per unit area s, to center of this disc is-

• A. $\frac{\sigma aQ}{\varepsilon_{0}}\left( \frac{2}{\pi}–\frac{1}{2} \right)$
• B. $\frac{\sigma aQ}{\varepsilon_{0}}\left( \frac{1}{2}–\frac{1}{\pi} \right)$
• C. $\frac{\sigma aQ}{\varepsilon_{0}}\left( \frac{1}{\pi}–\frac{1}{2} \right)$
• D. $\frac{\sigma aQ}{\varepsilon_{0}}\left( \frac{1}{2}–\frac{2}{\pi} \right)$

Answer 1

Answer: (B)

$\frac{\sigma aQ}{\varepsilon_{0}}\left( \frac{1}{2}–\frac{1}{\pi} \right)$

Answer 2