Question

A hot and a cold body are kept in vacuum separated from each other. Which of the following causes a decrease in temperature of the hot body?
A. Radiation
B. Convection
C. Conduction
D. Temperature remains unchanged

Answer 1

Hint- The heat always travels in three forms, radiation, conduction and convection. We will name them in the solution and then explain all of them one by one in the answer. Then see what is the correct option.

Complete Step-by-Step solution:
The heat travels in three forms: radiation, conduction and convection.
Conduction is the transfer of heat between substances that are in direct contact with one another. The better the conductor, the more quickly the heat will be moved. Metal is a decent conductor of heat. Conduction happens when a substance is heated, particles will acquire energy, and vibrate more. These atoms at that point bump with other particles and move a portion of their energy to them. This continues and passes the energy from the hot end down to the colder end of the substance.
Thermal energy is moved from hot spots to cold spots by convection. Convection happens when hotter territories of a fluid or gas ascend to cooler regions in the fluid or gas. Cooler fluid or gas at that point replaces the hotter territories which have ascended higher. This outcomes in a continuous flow design. Water bubbling in a container is a genuine case of these convection flows. Another genuine case of convection is in the air.
Radiation is a strategy for heat transfer that doesn't depend upon any contact between the heat source and the heated item similar to the case with conduction and convection. Heat can be transmitted through void space by warm radiation regularly called infrared radiation. This is a sort of electromagnetic radiation.
As the two bodies are kept in vacuum and without contact, conduction and convection are not possible. So, the heat has travelled from one body to the other in the form of radiation.
Thus, radiation (A) is the correct answer.

Note: No mass is traded and no medium is required during the time spent radiation. Instances of radiation is the heat from the sun, or heat discharged from the filament of a light bulb. The world's surface is warmed by the sun, the warm air rises and cool air moves in.