Question

Define athermanous substances & diathermanous substances. The emissive power of a sphere of area 0.02 m2 is 0.5 kcal s −1 m−2 . What is the amount of heat radiated by the spherical surface in 20 second​

Answer 1

DEFINITION OF DIATHERMONOUS SUBSTANCESB:Substances that don't allow transmission of infrared radiation through them are called diathermanous substances. - For example, rock salt, pure air, glass, etc.

DEFINITION OF ATHERMONOUS SUBSTANCES:

Substances which allow transmission of infrared radiation through them are called athermanous substances. - For example, wood, metal, CO2, water vapors, etc.

the amount of heat radiated by the spherical surface in 20 seconds is

( the solution is in the picture)

here is your answer N

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