Answer: 50 W.
- A 20 W
- B 50 W
- C 8 W
- D 200 W
Correct answer: B. 50 W
Explanation: By Fouriers law, H ∝ ΔT for fixed K, A, L. New rate = 20 × (25/10) = 50 W.
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.