Question

A hollow and a solid sphere of the same material and having identical outer surface are heated under the identical condition to the same temperature at the same time (both have the same e, a) :

• A. in the beginning both will emit equal amount of radiation per unit time
• B. in the beginning both will absorb equal amount of radiation per unit time
• C. both spheres will have same rate of fall of temperature (dT/dt)
• D. both spheres will have equal temperatures at any moment

Answer 1

The correct option is A in the beginning both will emit equal amount of radiation per unit time

The a hollow and a solid sphere of same material having identical outer surface are heated under identical condition of same temperature at same time then the solid sphere should expand slowly as it contain more mass heat plus transfer rate between particles are faster and to expand all the particles need to attain some energy at same temperature. While the hollow are contains air which prevent uniform heat distribution with in the sphere or rather slow distribution occurs. As it has less matter so molecular bond energy need to break and so expansion is rapid. Instead of expansion we might see explosion upon string heating.

Hence, the answer is in the beginning both will emit amount of radiation per unit time.