a) Electric charge

a) electric current as rate of flow of charge; I = ∆Q/∆t

b) the coulomb as the unit of charge

c) the elementary charge e equals 1.6×10^-19C

d) net charge on a particle or an object is quantised and a multiple of e

electric current = the rate of the flow of electric charge (the coulombs of charge that pass a specific point in a circuit per second)

• I = ∆Q/∆t

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

one coulomb of charge contains many electrons/protons

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

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

  • so charge is quantised

• the relative charge of an electron/proton is measured against the elementary charge

  • ±1e = ±1.6×10^-19C

• Q = ±ne

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