Electric Fields

Question 1

What is the definition of field strength?

Answer 1

Force experienced per unit charge by a SMALL, POSITIVE CHARGE (E=F/Q)

Question 2

What is the electric field strength of a uniform field?

Answer 2

E = V/d

Question 3

How do you calculate electric potential?

Answer 3

V = Ep/Q
Where V is electric potential, and Ep is electric potential energy

Question 4

What do lines of equipotential look like on a point charge and in a uniform field?

Answer 4

• Point charge: circular lines that are closer together near the centre.
• Uniform field: lines equally spaced out.

Question 5

How does electric field strength relate to electric potential?

Answer 5

Visualise a journey through a wire, to a plate, through a uniform field, to the next plate. While in the wire, the potential negligibly changes. As you move from one plate to the other, there is a change in potential. This change in potential over distance describes the electric field strength (E = V/d, so E / δV/δd). Therefore, on a graph of potential energy over distance, the Electric field is the NEGATIVE gradient of that graph.

Question 6

What is the equation for electric field around a point charge in terms of ε, and what does ε mean?

Answer 6

E = Q / 4πεr²
ε refers to the permeability of free space