Question
A charge of 8 mC is located at the origin. Calculate the work done in taking a small charge of –2 x 10–9 C from a point P(0, 0, 3 cm) to a point Q(0, 4 cm, 0), via a point R (0, 6 cm, 9 cm).
Solution
Given,
Charge, q =8 mC=8 x 10–3 C is located at origin and the small charge q0 =–2 x 10–9 C is taken from point P (0,0,3 cm) to a point Q (0,4 cm,0) through point R (0,6 cm,9 cm) as shown in the figure below.
Initial separation between q0 and q is rp = 3 cm = 0.03 m
Final separation between q0 and q is rQ = 4 cm = 0.04 m
Work done in taking the charge q0 from point P to Q does not dependent on the path followed and depends only upon rp and rQ i.e., initial and final positions.
Note: Point R is irrelevant to the answer.