a) electric charge

• define electric current

• state what this means mathematically

• the rate of the flow of electric charge

• the coulombs of charge that pass a specific point in a circuit per second

• state the formula for electric current

• I = ∆Q/∆t

• electric current (A) = the charge transferred (C) / time (s)

• explain the concept of elementary charge

• one coulomb contains many electrons/protons

• the elementary charge of each electron/proton in one coulomb is ±1.6×10^-19C

• explain how charge is quantised

• the charge of any charged object is a multiple of the elementary charge

• so charge is quantised

• explain the concept of relative charge

• relative charge is measured against the elementary charge

• ±1e = ±1.6×10^-19C

• the relative charge of an electron/proton = ±1e

• state the formula for the net charge of an object

• Q = ±ne

• net charge of an object (C) = number of electrons lost or gained × elementary charge