Calculate the number of units of electricity used if a bulb of 100 W is kept on for 5 hours.

The number of units of electricity consumed isn = (total wattage× time in hour)/1000Total wattage = 100 W      Time in hour = 5 hoursTherefore, n = (100×5)/1000= 0.5 unitsSo, the number of units of electricity consumed is 0.5 units.