A workshop uses heated plates to soften sheets of material. The plates are warmer than their surroundings.
An engineer tests two insulating mats placed beneath the plates. The mats have the same area and are tested with the same temperature difference across them. The measured rates are for energy transferred out of a heated plate through each mat.
| Mat | Thickness in mm\text{mm}mm | Thermal conductivity in W/m K\text{W/m K}W/m K | Measured rate of energy transfer in W\text{W}W |
|---|---|---|---|
| P | 20 | 0.12 | 60 |
| Q | 40 | 0.08 | 20 |
Explain which mat should be fitted to reduce unwanted energy transfer from a heated plate. Use all the information in the table.
Mat Q is compressed until its thickness is 20 mm. Its thermal conductivity does not change.
Explain how this would affect its rate of energy transfer and whether it would still transfer energy at a lower rate than mat P under the same test conditions.