JEE Physics 2025 Question with Solution

Given: A temperature difference in a material is used to convert heat energy into electrical energy.

Find: The required combination of thermal and electrical conductivity for efficient energy harvesting.

This is based on the Seebeck effect, where a temperature difference across a material generates an electric voltage.

For efficient thermoelectric conversion:

• Low thermal conductivity is needed so that heat does not flow away quickly and the temperature difference is maintained.
• High electrical conductivity is needed so that the generated charge carriers move easily and electric current is conducted efficiently.

If thermal conductivity is high, the temperature gradient reduces quickly, which weakens the thermoelectric effect. Therefore, the best material should have low thermal conductivity and high electrical conductivity.

The correct option is C.

Given: Heat energy is to be converted into electrical energy using a temperature difference.

Find: Which material property combination is most suitable.

1. A temperature difference in a material can generate voltage due to the Seebeck effect.
2. To keep generating voltage, the material must preserve the temperature gradient across it.
3. Therefore, the material should have low thermal conductivity, so heat is not transferred too rapidly.
4. The material should also allow charge to move easily.
5. Therefore, it should have high electrical conductivity.
6. Hence, the required combination is low thermal conductivity and high electrical conductivity.

Therefore, the correct option is C.