17) How much watt second in 1 watt hour?

18) What is the power if an emf of one volt causes a current flow of 1ampere?

19) Which is equal to electric power?

20) How much power does it consumes if an electric heater draws a current of 10 amps at 200 volts?

21) What is the resistance of an electric iron if the rating of electric iron is 220 V and 500 watts?