Fundamentals of Engineering Electromagnetics 1st Edition by David Cheng

Exercise 91

Calculate the energy expended in moving a point charge 500 (pC) from P 1 (2 , /3, 1) to P 2 (4, /2, 1) in an electric field E = a r 6r sin + a 3 r cos ( V/m ) by
a) first moving from = /3 to /2 at r = 2, then from r = 2 to 4 at = /2, and
b) first moving from r = 2 to 4 at = /3, then from = / 3 to /2 at r = 4.