Heat Transfer - Radiation: Practice Problem & Solution
Assertion (A): Two metallic spheres of same size, one of copper and the other of aluminium, heated to the same temperature, will cool at the same rate when they are suspended in the same enclosure. Reason (R): The rate of cooling of a body depends only on the excess of temperature of the body over the surroundings.
Solution Explained:
To solve this problem, we apply the core principles of Heat Transfer - Radiation. Understanding the underlying formula is key to arriving at the correct answer below:
Assertion (A) is false because cooling rate depends on material properties like specific heat capacity and emissivity, which differ for copper and aluminium. Reason (R) is false.
Newton's Law of Cooling shows rate depends on surface area and emissivity, not just temperature difference.
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