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 contains many electrons/protons

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

  • the charge of any charged object is a multiple of the elementary charge, so charge is quantised

• relative charge is measured against the elementary charge

  • ±1e = ±1.6×10^-19C

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

most charged objects have either lost (gained a positive charge) or gained (gained a negative charge) electrons

• Q = ±ne

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