When voltage drops, current rises ! The reason we transmit power at high voltages like 11kV and up is because the current falls. take a 240 volt supply and put a 1kW load on it. 1000W/240v= 4.16 Amps. Run the same load on 100V and you get 1000w/100V= 10Amps Resistance is measured in ohms, but power dissipated is in WATTS The resistance of any heating element will not give a true current reading when applied to a circuit using alternating current. Hence a 3kW fan heater on 240V draws a current of 3000/240=12.5 amps Pedants be aware that this is a simplified version of the truth!!!