Question

an electric bulb of hundred what is used for 10 hours per day calculate the unit of energy consumed in 1 day by the bulb

Answer 1

100 Watt bulb used for 10 hours will consume :
100 × 10 = 1000 Watt-Hour = 1 Kilowatt-Hour (kWH) = 1 units.
 'OR'
Power = Energy/Time 
100 = Energy/(10×60×60 sec) 
Energy = 36000 sec x 100 watt = 3600000 Joules.