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JEE Main 2025 Jan 29 Shift 2, Physics Q1: Electromagnetic Waves

JEE Main2025Jan 29, Shift 2Physics
Q.

The difference of temperature in a material can convert heat energy into electrical energy. To harvest the heat energy, the material should have

  1. A

    low thermal conductivity and low electrical conductivity

  2. B

    high thermal conductivity and high electrical conductivity

  3. C

    low thermal conductivity and high electrical conductivity

  4. D

    high thermal conductivity and low electrical conductivity

Solution

Conversion of a temperature gradient into a voltage is the Seebeck effect, the principle behind thermoelectric generators.

To be useful as a thermoelectric harvester, the material must (i) maintain the temperature difference between its hot and cold ends — this needs low thermal conductivity so that heat does not short-circuit through the bulk — and (ii) carry the resulting current with little Joule loss, which needs high electrical conductivity.

Option (3) is correct.

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