A laboratory technician wishes to design a heating element that radiates energy…
PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
A laboratory technician wishes to design a heating element that radiates energy efficiently into the room.
Answer the following questions with suitable reasons:
(i) How does the total thermal energy emitted per unit time by a body depend on its surface area, if all other factors remain unchanged?
(ii) Keeping surface area fixed, explain how the rate of emission depends on the absolute temperature of the body.
(iii) Describe the role of the surface nature of the body in thermal radiation. Define emissivity and state its possible range of values.
(iv) The coils of electric room-heaters are usually coated with a dull black oxide layer. Explain why this practice improves the performance of the heater.