Infrared radiation is detected by

$A$ solid cylinder of length $L$ and radius $r$ is heated up to the same temperature as that of a cube of edge length $a$. If both have the same material,volume,and are allowed to cool under similar conditions,then the ratio of the amount of radiation emitted will be (Neglect radiation emitted from the flat surfaces of the cylinder).

When we enter an air-conditioned room,we feel cold. This can be explained by:

When a body has the same temperature as that of its surroundings,which of the following statements is true?

Which of the following statements is true for a perfectly black body?

Heat radiations propagate with the speed of