Charge and current

Mean drift velocity

The average rate of change of displacement of a charge carrier attained due to an electric field

Conductor

A material with a low resistance and a high number density

Insulator

A material that does not easily support an electric current due to having a high resistance and a very low number density

Number density, n

The number of free charge carriers per unit volume

Kirchoff's First Law

The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that point

Kirchoff's First Law is effectively equivalent to what?

The conservation of charge

Electrolyte

A liquid that contains ions that are free to move and so conducts electricity

Cation

A positively charged ion

Anion

A negatively charged ion

Ion

An atom that has either lost or gained electrons and so has a net charge

Free electron

An electron in a metal that is not bound to an atom and is free to move

What are free electrons also referred to as?

Delocalised electrons

Relative charge

The charge of a particle measured in terms of the elementary charge, e

Elementary charge, e

The charge on one proton, equal to 1.60×10^-19C

Conventional current

DIrection of flow of positive charge, which is opposite to the direction of the flow of electrons

Electric current

The rate of flow of positive charge, usually measured in amperes

Conservation of charge

Charge cannot be created nor destroyed

Semiconductor

A material with an intermediate resistance and number density

What can the value of number density (n) can be affected by?

The value of n can often be affected by temperature or illumination