Question

A 100 W electric bulb is used for 5 hours daily. What is the energy consumed in 30 days?

• A. 15 kWh
• B. 10 kWh
• C. 5 kWh
• D. 20 kWh

Answer 1

The Correct Option is A

Step 1: Convert Power from Watts to Kilowatts
Power is usually given in watts (W), but for calculating energy consumption in kilowatt-hours (kWh), it needs to be converted to kilowatts (kW).
100 watts = 100 ÷ 1000 = 0.1 kW

Step 2: Calculate Total Time of Usage
Suppose the electrical device is used for 5 hours per day over a period of 30 days:
Total usage time = 5 hours/day × 30 days = 150 hours

Step 3: Calculate Energy Consumed
Energy consumed (E) is calculated using the formula:
Energy (kWh) = Power (kW) × Time (hours)
Substituting the values:
E = 0.1 kW × 150 hours = 15 kWh

Final Answer:
15 kilowatt-hours (kWh)