Electric Field Problem Set
1 A proton is released in a uniform electric field, and it experiences an electric force of
3.75x10-14 N toward the south. What are the magnitude and direction of the electric field?
2 What are the magnitude and direction of the electric field at a point midway between a +8.0
μC and a -7.0 μC charge 8.0 cm apart? Assume no other charges are nearby.
3 (a) Determine the electric field at the origin 0 due to the two charges
at A and B. (b) Repeat but let the charge at B be reversed in sign.
a)
4 An electron (mass m=9.11x10 -31 kg) is accelerated in the uniform field
(E=1.45x104 N/ C) between two parallel charged plates. The separation of the
plates is 1.10 cm. The electron is accelerated from rest near the negative plate
and passes through a tiny hole in the positive plate. (a) With what speed does
it leave the hole? (b) Show that the gravitational force can be ignored.
5 In a simple model of the hydrogen atom, the electron revolves in a circular orbit around the
proton with a speed of 1.1x106 m/s. Determine the radius of the electron’s orbit.