(a)[1]
State what the term field of force means.
(b)[3]
Gravitational fields and electric fields can both be described as fields of force. State one similarity and one difference between these two fields of force.
(c)[3]
Two protons are isolated in space, and their centres are separated by a distance $R$. Treat each proton as both a point mass and a point charge. Determine the magnitude of the ratio $$\frac{\text{force between protons due to electric field}}{\text{force between protons due to gravitational field}}.$$