electricity

current

the rate of flow of electric charge.

direct current

in a circuit the current is always in the same direction in the circuit.

alternating current

the current in a circuit continually changes direction backwards and forwards in a circuit.

resistance 

The opposition in an electrical component to the movement of electrical charge through it.

charge

a property of a body which experiences a force in an electric field

potential difference (voltage)

the work done in moving one coloumb of charge between two points/ the energy per unit of charge

power

The energy transferred each second, measured in watts (W).

Emf

energy supplied to every coulomb of charge (electromotive force)

Emf formula

I(r+R)

Lost volts

Ir

Vtpd

IR

Emf and internal resistance graph

Imax

short circuit current (R=0)

capacitance

charge stored per unit voltage

the effect of capacitance on charging current graph

the effect of resistance on charging current graph

Vrms

Vpeak/√2

circuit rules