Question

Picking up a hot coffee, your hands feel warm:
This is due to which of the following phenomena
A) Conduction
B) Convection
C) Radiation
D) All of these

Answer 1

Hint: In conduction process particles don't move from the place but they can vibrate about their initial position. And in case of convection particles move from a place to another and in case of radiation no medium is required to transfer heat from a place to another.

Complete step by step solution:
The molecules are very close to each other in the material and hence when a cup is filled with the hot material then the heat is transferred to the immediate molecules and continuous passing of heat makes the surface of cup warm from outside.
Hot coffee cup in the shape of a cylinder or can be treated as a hollow cylinder. Inner portion of the cup having high temperature can be treated as a hot reservoir and the outer surface can be treated as a lower temperature reservoir.
The heat flown here by the cup material molecules as they vibrate around their position by the resulting heat energy here is transferred by conduction process.
Initially there will be an unsteady flow of heat and after a certain time steady state is found and final heat current flows at a constant rate.

Hence option A is the correct answer.

Additional information:
Let us read some other modes of transfer of heat.
Conduction: The act of conducting or conveying is transmission through or by means of a conductor, the transfer of heat through matter by communication of kinetic energy from particle to particle with no net displacement of the particles compare convection, radiation
Convention: Conduction is the way in which energy is transferred (through heating by contact) from a hot body to a cooler one (or from the hot part of an object to a cooler part).
Radiation: Radiation is the process in which energy is emitted as particles or waves. The process in which energy is emitted by one body, transmitted through an intervening medium or space, and absorbed by another body.
There are some of the examples of the radiation:
1. A burning candle emits radiation in the form of heat and light.
2. Microwaves
3. Waves produced by mobile phones.
4. A campfire’s heat
5. Taking heat from the fire during the cold season is also an example of radiation.
6. Decaying of the radioactive elements in the form of alpha particles.

Note: In short we can treat the cup as a cylinder so the conduction of heat will be done radially through a hollow cylinder. The better the conductor, the more rapidly heat will be transferred. That’s why metal is the good conductor of electricity. When a particle gets heated more it gets more energy and hence vibrates more.