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A student has a battery-powered torch - Edexcel - GCSE Physics - Question 6 - 2017 - Paper 1
Question 6
A student has a battery-powered torch. When the lamp in the torch is lit for 10 s, 9 J of energy is transferred in a useful way and 61 J is wasted. Complete the ta... show full transcript
Worked Solution & Example Answer:A student has a battery-powered torch - Edexcel - GCSE Physics - Question 6 - 2017 - Paper 1
Step 1
Complete the table
Answer
To complete the table, we need to distribute the total energy of 70 J into the forms given:
- Thermal (heat): 61 J (wasted energy)
- Light: 9 J (useful energy)
- Electrical: 70 J (total energy supplied)
Thus, the completed table will look like this:
| form of energy | amount of energy in 10 s / J |
|---|---|
| thermal (heat) | 61 |
| light | 9 |
| electrical | 70 |
Step 2
Explain why the temperature of the filament in the lamp remains the same
Answer
The temperature of the filament in the lamp remains constant despite ongoing electricity supply due to thermal equilibrium. Once the filament reaches a steady high temperature, the heat energy being dissipated as light and thermal energy equals the heat energy generated from electrical energy.
Thus, even though electricity continues to flow through the filament, the heat generated and lost balance out, maintaining the temperature at a stable level.