An electron is taken from point A to point B along the path AB in a uniform electric field of intensity  E=10  Vm−1. Side AB = 5 m, and side BC= 3 m. Then, the amount of work done on the electron by us is

WAB=WAC+WCBWCB should be zero, because in moving from C to B, we always move perpendicular to filed. Hence, force applied by field and displacement will be at 900.WAC=−e(VC−VA)VC−VA=−E×AC=−10×4=−40∴WAC=−e×(−40)=40eSo WAB=40  eV