Question

There are two large parallel metallic plates S1 and S2 carrying surface charge densities l1 and l2 respectively (l1 > l2) placed at a distance d apart in vacuum. Find the work done by the electric field in moving a point charge q a distance a (a

Answer 1

Answer:

Explanation:

electric field for area 1, 2 and 3 is E1, E2 and E3 respectively.

=> E1 = q1 + q2 / 2ε。

=> E2 = q1 - q2 / 2ε。

=> E3 = q1 + q2 / 2ε。

=> The value of potential Va is zero at point A because A point is on the S1.

∴Va = 0

=> The value of potential Vb at point B is (q1 + q2 / 2ε。) a

∴Vb =  (q1 + q2 / 2ε。) a

work done by the electric field:

w = qΔV      [but ΔV =Vb-Va]

∴ w = q*(Vb-Va)

= q*(a(q1 + q2 / 2ε。- 0)

= qa (q1 + q2 / 2ε。)