Edexcel iGCSE Physics (4PH1) 4.1 Units Exam Style Question Paper 2B - New Syllabus
Question
This question is about generating electricity from renewable energy resources.
(a) Photograph 1 shows a solar farm in the United Kingdom and photograph 2 shows a geothermal power station in Iceland.
Discuss the advantages and disadvantages of generating electricity using solar power and geothermal resources.
(b) A student investigates how the amount of light affects the output voltage of a solar cell. Photograph 3 shows how the student sets up their equipment.
(i) The student varies the distance between the solar cell and the lamp and measures the output voltage of the solar cell at each distance. The student’s results are shown below.
Draw a table showing the student’s results.
(ii) Give a control variable for the student’s investigation.
(iii) The student states that the solar cell could be used as a power source for the lamp. They suggest that this would work if:
- the solar cell is connected directly to the lamp
- the light from the lamp is used to produce the output power from the solar cell
Explain, with reference to the principle of conservation of energy, why the student’s suggestion would not work.
Syllabus Topic Codes (Edexcel International GCSE Physics 4PH1):
• 4.3: Conservation of Energy — part (b)(iii)
• 4.2: Energy Stores and Energy Transfer Pathways — part (b)(iii)
▶️ Answer/Explanation
(a) Advantages and disadvantages of solar and geothermal power
Solar power:
- Advantage: Produces no noise.
- Advantage: Produces no greenhouse, polluting, or harmful gases during electricity generation.
- Advantage: Solar energy is available in many locations.
- Disadvantage: Electricity generation depends on the amount of sunlight available.
- Disadvantage: A large area may be required for solar panels.
Geothermal power:
- Advantage: It can be used throughout the day and is not dependent on sunlight.
- Advantage: It requires a relatively small amount of space.
- Advantage: It produces very little or no noise.
- Disadvantage: It is not available in all locations.
- Disadvantage: It may release greenhouse, polluting, or harmful gases.
- Disadvantage: There is a possible risk of groundwater pollution.
The main comparison is that solar power is widely available but depends on sunlight, whereas geothermal power can provide a more continuous supply but is restricted to suitable geological locations.
(b)(i) Results table
The results should be organised into two columns with clear headings and units.
| Distance between lamp and solar cell | Output voltage |
|---|---|
| Include the appropriate unit from the results | Include the appropriate unit from the results |
All the values should be copied accurately and recorded to the same number of decimal places as originally given.
(b)(ii) Control variable
One suitable control variable is the power or brightness of the lamp.
Other acceptable answers include the amount of background light or the light intensity of the lamp.
(b)(iii) Conservation of energy [3 marks]
- The lamp and solar cell are not 100% efficient, so some energy is transferred to unwanted forms.
- Not all of the light produced by the lamp is received by the solar cell.
- Some energy is lost to the surroundings, for example as thermal energy in the lamp, solar cell, or connecting wires.
Therefore, the solar cell cannot produce enough electrical energy from the lamp’s light to continuously power the same lamp. This would require more useful energy to be produced than is supplied, which contradicts the principle of conservation of energy.