Ohm’s law
       Potential difference (V) = Current (I) x resistance (R)
Units  - Potential difference is in (Volts) Current is in Amps and resistance is in Ohms
       V   =  I x R (to work out the voltage when you know the current and resistance)
       R   = V ÷ I (to work out the resistance when you know the voltage and current)
        I   = V ÷ R (to work out the current when you know the voltage and resistance)

Power equation
      Power is the rate at which energy is transformed in a device ( i.e. Power =
energy ÷ time)
In electrics power can easily be worked out by multiplying current by
potential difference
       Power (P)   = Potential difference (V) x Current (I)
Units - Power is in Watts, Potential difference is in Volts and current is in Amps
        P = V  x  I  ( to work out power when you know the voltage and current)
            V = P ÷ I    (to work out voltage when you know the power and current)
        I = P ÷ V    (to work out current when you know the power and voltage)

The next equations  are for pupils taking higher tier
Energy transformed
        Energy transformed (E) = Current (I) x Potential difference (V)
Units - Energy is in Joules, current is in Amps and potential difference is in Volts
E = I x V,                                 I = E ÷ V,                                       V = E ÷ I


Flow of charge (current is the rate of flow of charge)
Charge (Q) = Current (I) x time (t)
Units – Charge is in Coulombs, current is in Amps and time is in seconds