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⚛️ Physics  ·  Thermal Properties of Matter  ·  NEET & JEE

A metal rod of length 1 m has a coefficient of linear expansion 2 × 10⁻⁵ /°C. If its temperature increases by 50°C, the increase in length is:

Answer: 1 mm.

  • A 0.1 mm
  • B 1 mm
  • C 0.5 mm
  • D 0.01 mm

Correct answer: B. 1 mm

Explanation: ΔL = αLΔT = 2×10⁻⁵ × 1 × 50 = 1×10⁻³ m = 1 mm.

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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