Question

At what speed does heat radiation travel? What path does it follow?

Answer 1

Hint: Radiation is the fastest mode of transmission of heat. It is the result of the random motion of the molecules within the matter. Heat radiation uses electromagnetic waves to transfer heat. Thus, find the relation between speed of light and electromagnetic waves. From that relation, you can obtain the speed at which heat radiation travels and which path it follows.

Complete answer:
Heat radiation is defined as a process in which heat gets transferred. It is also known as Thermal radiation. The transfer of heat takes place from an object with higher temperature to an object with lower temperature. It uses electromagnetic waves to transfer heat from one place to another. The electromagnetic it uses is infrared waves.
Speed of electromagnetic waves is the same as that of the speed of light. Thus, the speed of electromagnetic waves is $3× {10}^{8} {m}/{s}$. As radiation uses electromagnetic waves to transfer heat, it’s speed will also be the same as the speed of light. Thus, the speed of heat radiation is $3× {10}^{8} {m}/{s}$ and it does not need any medium to travel.
Heat radiation travels along a straight line. But, it travels only through transparent, such as glass, water, etc.
Hence, heat radiation travels at a speed of $3× {10}^{8} {m}/{s}$. And it follows a straight line.

Additional Information:
Heat can be transferred from one place to another in three different ways namely Convection, Conduction and Radiation. The transfer of heat through liquids and gases is due to Convection. Conduction is mostly seen in solids. And Radiation does not need any medium to transfer heat.

Note:
Radiation is the process behind the transmission of heat from the Sun to Earth. The radiation from the Sun is a mixture of electromagnetic waves. This radiation is a mixture of infrared and ultraviolet waves. Thus, we can say, solar radiation is a form of electromagnetic wave.