Question

In which of the following phenomena, the heat waves travel along straight lines with the speed of light?
A. Thermal conduction
B. Forced convection
C. Natural convection
D. Thermal radiation

Answer 1

Hint:Radiation is the quickest route of heat transmission. It is caused by the random motion of molecules within matter. Heat radiation transfers heat by using electromagnetic waves. As a result, determine the relationship between the speed of light and electromagnetic waves.

Complete answer:
Energy transfer refers to the movement of energy from one location to another. Heat transfer is mostly caused by temperature differences.There are several modes of heat transfer:-
Thermal conduction: The passage of thermal energy (heat) within one material or between materials in contact is referred to as thermal conduction.

Forced convection: Forced convection is a method of heat transfer in which fluids are forced to circulate to increase heat transmission. This can be accomplished with a ceiling fan, a pump, a suction device, or another device. Many people are familiar with the phrase "heat rises."

Natural convection: Natural convection is a type of convection heat transfer in which the bulk motion or advection is driven by self-induced forces. Temperature or concentration gradients may be causing these forces.

Thermal radiation: Thermal radiation is the process by which energy is radiated in all directions by a heated surface and travels straight to its site of absorption at the speed of light; thermal radiation does not require an intervening medium to transfer it.
Hence, among all the given alternatives, thermal radiation is the mode of heat transfer in which heat waves travel along straight lines with the speed of light.

Therefore, the correct option is D.

Note: It should be emphasised that radiation is the process by which heat is transmitted from the Sun to Earth. The Sun's radiation is a complex blend of electromagnetic waves. This radiation consists of a combination of infrared and ultraviolet wavelengths. As a result, we can say that solar radiation is a type of electromagnetic wave.