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2(a) A 100 W filament lamp is 15% efficient - Edexcel - GCSE Physics - Question 2 - 2012 - Paper 1
Question 2
2(a) A 100 W filament lamp is 15% efficient. (i) Explain the meaning of the term 15% efficient. (ii) Draw a labelled energy flow diagram to show what happens to 100... show full transcript
Worked Solution & Example Answer:2(a) A 100 W filament lamp is 15% efficient - Edexcel - GCSE Physics - Question 2 - 2012 - Paper 1
Step 1
(i) Explain the meaning of the term 15% efficient.
Answer
The term "15% efficient" indicates that out of the total electrical energy supplied to the lamp, only 15% is converted into useful energy, specifically in the form of light. Therefore, if the lamp receives 100 J of electrical energy, 15 J is transformed into light energy, while the remaining 85 J is not utilized effectively and is dissipated as waste energy, mainly as heat.
Step 2
(ii) Draw a labelled energy flow diagram to show what happens to 100 J of electrical energy supplied to the lamp.
Answer
To represent the energy flow diagram:
- Start with a box labeled "100 J Electrical Energy."
- From this box, draw an arrow pointing to a new box labeled "15 J Light Energy" to represent the useful energy output.
- Draw another arrow subtitled "Waste Energy" pointing to a box labeled "85 J Heat Energy" to depict the lost energy.
- Clearly label both arrows to show the flow of energy from the electrical input to the light output and waste heat.