Question

An electron (charge =-1.6*10^-19C) moves on a path parallels but opposing a uniform electric field of strengths 2.3 N/C. How much work is done on the on the electron a sit moved 20cm? How much work is done on the electron if it moves perpendicular to the electric field?

Answer 1

Given that :

charge on electron, q = -1.6 x 10^-19 C

electric field strength, E = 2.3 N/C

distance, s = 20 cm = 0.2 m

Work is done on the electron which will be given as :

W = F s cos                                           

where, F = electric force = q E

W = (q E) s cos    

inserting the values in above eq.

W = (-1.6 x 10^-19 C) (2.3 N/C) (0.2 m) cos 0⁰                                  (since, = 0 degree)

W = - 0.736 J

if it moves perpendicular to the electric field, then work done on the electron which will be given as ::

W = (-1.6 x 10^-19 C) (2.3 N/C) (0.2 m) cos (90)⁰                                 (since, = 90 degree)

W = 0 J

Charged particles which moving perpendicular to the electric field lines must be moving along equipotential lines, so the work done is zero.