Question

An electric bulb of 40 Watt is used for 8 hours along with a fan of 60 W for 12 hours. The Daily consumption of energy is ___________ units. 
1. 1.2
2. 1.08
3. 1.04
4. 1.4

Answer 1

Correct Answer - Option 3 : 1.04

Concept:

Commercial unit of Energy

The commercial unit of energy is kilowatt hour (kWH)

If an electric device of power ratted 1 kilowatt is used for 1 hour, the commercial energy consumed is  kilowatt hour. 

The electricity company charge us by this rate. 

Calculation:

Power of bulb = 40 Watt = 0.04 kWH. 

time of consumption t₁ = 8 hrs

Total energy consumption = power × time = 0.04 kWH × 8 = 0.32  kWH 

Power of Fan = 60 Watt = 0.06 kWH. 

time of consumption t1 = 12  hrs

Total energy consumption = power × time = 0.06 kWH × 12 = 0.72  kWH 

Total unit consumption = 0.32  kWH  + 0.72  kWH = 1.04 kWH

So, the correct option is 1.04 units. 

1 unit = 3.6 × 10⁶ Joules