Question

A hot and a cold body are kept in a vacuum separated from each other. Which of the following causes a decrease in the temperature of the hot body?

• A. Radiation
• B. Convection
• C. Conduction
• D. Temperature does not change

Answer 1

The correct option is A

Radiation

The explanation for the correct answer

Option (A): Radiation.

1. Heat transfer - It is the transfer of energy from one location to another. This can take place in 3 ways, namely Conduction, Convection, and Radiation
2. Radiation-The process in which heat transfer occurs without being in contact and without disturbing the particles of the medium
3. In a vacuum and with no contact, heat can only be transferred by Radiation
4. Heat moves from the hot body to the surroundings
5. Due to the loss of heat, the temperature of the hot body decreases.

The explanation for the incorrect answer:

Option (B): Convection

1. Convection - When liquid molecules carry out the transfer of energy, the process is called convection. This process occurs only in fluids.
2. In a vacuum, there are no particles. Therefore heat can not be transferred by convection

Option (C): Conduction

1. Conduction - When energy is transferred from one body to another through direct contact, the process is called conduction. This process is applicable only to solids.
2. The bodies are kept apart so there is no contact between them. Therefore heat cannot be transferred by conduction

Option (D): Temperature does not change

1. The hot body will lose heat energy to its surroundings whatsoever.
2. Whenever there is a transfer of heat, there is a change in temperature.Therefore we cannot say that the temperature is unchanged

Hence we can say radiation causes a decrease in the temperature of the hot body & option A is correct.