Question

The electrical energy (in kWh) consumed in operating a bulb of 40 W for 5 hours a day in a month of 30 days is

• A. 12
• B. 6
• C. 3
• D. 1.5

Answer 1

The Correct Option is B

The electrical energy (in kWh) consumed in operating a bulb of 40 W for 5 hours a day in a month of 30 days is: 

First, calculate the total energy consumed by the bulb in a day: $$E_{\text{day}} = P \times t = 40 \, \text{W} \times 5 \, \text{hours} = 200 \, \text{Wh}$$ 

Next, calculate the total energy consumed in a month of 30 days: $$E_{\text{month}} = E_{\text{day}} \times \text{Number of days} = 200 \, \text{Wh} \times 30 = 6000 \, \text{Wh}$$ 

Finally, convert the energy from Wh to kWh: $$E_{\text{kWh}} = \frac{6000 \, \text{Wh}}{1000} = 6 \, \text{kWh}$$ 

Thus, the electrical energy consumed is 6 kWh.