A workshop uses solar cells to supply a ventilation system during working hours. Measurements are taken at the same time on two days.
| Weather | Solar-cell output | Ventilation-system demand |
|---|---|---|
| Clear sky | 9.2 kW | 6.0 kW |
| Thick cloud | 2.1 kW | 6.0 kW |
The measurements provide evidence that
solar cells are reliable because their output on the clear day exceeds the demand.
solar-cell output depends on the weather, so it may not meet the ventilation-system demand.
solar cells are reliable because their output can be raised whenever demand rises.
the extra output on the clear day can supply the ventilation system on the cloudy day.
86 exam-style questions on AQA GCSE Physics 1.3 National and global energy resources, covering 1.3 National and global energy resources. Each one has a worked solution and a mark scheme showing where the marks go.