Electric Fields

Question 1

Electrical conductors

Answer 1

Including metals, contain lots of free electrons.

Question 2

Electrical insulating materials

Answer 2

Do not contain free electrons, all the electrons in an insulator are attached to individual atoms.

Question 3

Line of force / Field line

Answer 3

The path a free positive test charge follows.

Question 4

Electrical field strength, E

Answer 4

The force per unit charge on a positive test charge placed at that point. E = F/Q = V/d, unit is N C^-1.

Question 5

Electric potential

Answer 5

The work done per unit positive charge on a positive test charge. V = Ep/Q, unit = V.

Question 6

Equipotentials

Answer 6

Surfaces of constant potential. A test charge moving along an equipotential has constant potential energy. No work is done by the electric field on the test charge because the force due to the field is at right angles to the equipotential.

Question 7

Coulomb’s law

Answer 7

F = kQ1Q2 / r^2