WJEC AS Physics Unit 2.1 + 2.2

Unit of charge

Coulomb (C)

The net charge in a system remains constant (provided charges can’t enter or leave)

Electron’s charge

Charge of one electron is a very small fraction of a Coulomb

1.6×10^-19C

Conductors

Materials through which a charge can flow

Electricity

The flow of electric charges through a conductor in one direction

Electric current

Derivation of I=nAve

Potential difference

The pd between two points is the energy converted from electrical potential energy to some other form per coulomb of charge flowing from one point to the other. Unit; V (JC^-1)

The Volt

Resistance

I-V graphs for the filament of a lamp at constant temperature

I-V graphs for a metal wire at constant temperature

Ohms Law

Definition of resistance

Restivity

Power

Deriving the power equations

Superconductivity

Superconducting temperature

Uses of superconductors

Law of conservation of charge

Current in a parallel circuit

Current in a series circuit

Potential difference in series circuits

Potential difference in parallel circuits

Resistance in series circuits

Resistance in parallel circuits

Potential divider

Uses of potential dividers in circuits

Circuits containing an LDR and a fixed resistor to form a potential divider

Circuits containing a thermistor and a fixed resistor to form a potential divider

emf of a source, E

Internal resistance

Current in a circuit containing multiple cells in series

Potential difference in a circuit containing multiple cells in series