Question

A uniform electric field is produced between two parallel plates that have a PD of 100V across
them and separated by a distance of 20mm.

CONSTANTS
Acceleration due to gravity = 9.82 = m 2
s
Eo m
= s − 889 12 .
Speed of light = 3 108 x m
s Mass of an Electron = 911 10 31 . x kg −
Mass of proton = 1 67 10 27 . x kg − Charge on an Electron = 1 6 10 19 . x C −
Charge on proton = Planck’s Constant =
1eV = 1.6x10-9J

ii) Calculate
a) The force electron on an electron in the field. (6 marks)
b) The work done in moving an electron from one plate to another in
the field.

Answer 1

a)

$$F=e\frac{V}{d}$$

$$F=(1.6\cdot10^{-19})\frac{100}{0.02}=8.0\cdot10^{-16}N$$

b)

$$W=eV=(1.6\cdot10^{-19})100=1.6\cdot10^{-17}\ J$$