A builder compares four walls for a new house. Each wall is made from a different material.
Table
| Wall | Relative thermal conductivity of material | Thickness of wall (cm\text{cm}cm) |
|---|---|---|
| P | 0.8 | 20 |
| Q | 0.2 | 10 |
| R | 0.2 | 30 |
| S | 1.5 | 30 |
Which wall would make the house cool most slowly?
Wall P
Wall Q
Wall R
Wall S
50 exam-style questions on OCR GCSE Physics 7.2 Power and efficiency, covering 7.2.1 Dissipation of energy, 7.2.2 Energy transfers in domestic devices, 7.2.3 Power ratings of domestic appliances, 7.2.4 Efficiency of energy transfers, 7.2.5 Ways to increase efficiency, 7.2.6 Reducing unwanted energy transfers, and 7.2.7 Thermal conductivity and the cooling of buildings. Each one has a worked solution and a mark scheme showing where the marks go.