a) 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

current = the rate of flow of charge

I = Q/t

• current (A) = charge (C) / time (s)

one coulomb of charge contains many electrons/protons

the elementary charge of each electron/proton = ±1.6×10^-19C

charge is quantised because the charge of a charged object is multiple of elementary charge

relative charge is measured against elementary charge

• ±1e = ±1.6×10^-19C

Q = ±ne

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