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⚛️ Physics  ·  Thermal Properties of Matter  ·  NEET & JEE

According to the Stefan-Boltzmann law, the power radiated by a perfect black body is proportional to:

Answer: T⁴.

  • A T
  • B
  • C
  • D T⁴

Correct answer: D. T⁴

Explanation: Stefan-Boltzmanns law states E = σT⁴, so radiated power per unit area is proportional to the fourth power of absolute temperature.

Heating Curve: Ice → Water → SteamHeat added (Q)T (°C)ice warms (-ve→0°C)melting (0°C, latent heat)water warms (0→100°C)boiling (100°C, latent heat)FLAT regions = phase change (all heat goes into breaking bonds, NOT raising temperature)

During a phase change (melting or boiling), temperature stays constant while heat is absorbed entirely as latent heat (Q=mL); temperature only rises again once the substance is fully in its new phase.

Concept context

Temperature scales, thermal expansion, calorimetry, and the three modes of heat transfer including radiation laws.

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