Physics
Grade-9
Easy
Question
What is the efficiency of incandescent bulbs?
- Less than 10 %
- More than 15%
- Between 10% and 15%
- Cannot say
Hint:
Approximately 2% of the emitted energy from an incandescent source is useable visible light with the remaining 98% being wasted heat.
The correct answer is: Less than 10 %
- Energy input = useful energy output + waste energy
- Efficiency (%) = (useful energy output ÷ energy input) × 100
- Approximately 2% of the emitted energy from an incandescent source is useable visible light with the remaining 98% being wasted heat
. Incandescent bulbs are likely to burn out frequently and require replacement each year.
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