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⚛️ Physics  ·  Thermal Properties of Matter  ·  NEET & JEE

A star has a surface temperature twice that of the Sun. According to Wiens law, the peak emission wavelength of the star compared to the Sun is:

Answer: Half as long.

  • A Twice as long
  • B Half as long
  • C Same
  • D Four times as long

Correct answer: B. Half as long

Explanation: Wiens law: λ_m ∝ 1/T. Doubling temperature halves the peak wavelength, so the star peak wavelength is half that of the Sun.

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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