Question

two charges -q and +q are located at points A(0,0,-a) and B(0,0,+a) respectively. how much work is done in moving a test charge from point P(7,0,0) to Q(-3,0,0)?

Answer 1

-q charge is at (0,0,-a)
+q charge is at ( 0,0,a)
Work done will be zero because coordinates of x and y are zero so distance travelled by charge is zero so the work done will be zero as
0 × f cosx + 0 fcos x {= zero