past paper notes- electric fields

Question 1

For any point outside a spherical conductor, the charge on the sphere may be considered to act as a point charge at its center. By reference to electric field lines, explain this. /2

Answer 1

The electric lines are radial.
Electric lines originate from center.

Question 2

Explain why gravitational forces are not considered when calculating the force between charged particles? /1

Answer 2

electric force is much greater than gravitational force

Question 3

State one similarity and one difference between the fields of force produced by an isolated point charge and isolated point mass. /2

Answer 3

similarity: both are radial

difference:
1) direction is always towards the mass
2) direction can be away or towards the charge

Question 4

state the relationship between electric potential and electric field strength at a point?/2

Answer 4

electric field strength is equal to negative potential gradient