Question

A furnace uses 1000 kJ of fuel energy.
Useful heat output = 700 kJ.
What is the furnace efficiency?

• A. 50%
• B. 70%
• C. 80%
• D. 30%

Hint:

To calculate efficiency, always divide the useful energy output by the total energy input and multiply by 100 to get the percentage.

Answer 1

The Correct Option is B

Efficiency (η) is calculated using the formula:
η = (Useful heat output / Total energy input) × 100

Given:
- Total energy input = 1000 kJ
- Useful heat output = 700 kJ

Substituting the values:
η = (700 / 1000) × 100 = 70%

Thus, the furnace efficiency is 70%.