Specific heat capacity of water is 4200 J/kg°C. How much heat is required to raise temperature of 2 kg water by 10°C?
A. 84000 J
B. 4200 J
C. 8400 J
D. 42000 J
Answer: Option A
Solution (By JKExamLibrary)
Q = mcΔθ = 2 × 4200 × 10 = 84,000 J = 84 kJ. Large specific heat of water makes it useful for cooling and climate moderation. Always check units: mass kg, c J/kg°C, ΔT °C.
Explanation:
Microwave ovens use electromagnetic radiation in the microwave frequency range (usually around 2.45 GHz). Water molecules have a permanent electric dipole moment. The oscillating electric field of the microwaves rapidly forces the water molecules to flip back and forth to align with the field, generating thermal energy via friction and effectively heating the food from within.
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