Methods of heat transfer

Question 1

Why do objects transfer heat?

Answer 1

If two objects with two different temperatures meet, then they need to reach a thermal equilibrium. The thermal energy from the object with the higher temp flows into the object with lower temp, till the 2 objects have the same temp., attaining thermal equilibrium.

Question 2

What are the methods of heat transfer?

Answer 2

1. Conduction - any heat which you feel from contact
2. Convection - any heat moving upwards
3. Radiation any heat you feel from afar

Question 3

Explain conduction

Answer 3

In solids, conduction is very efficient. When two solids meet, they want to reach a thermal equilibrium. The particles of the warmer solid start to vibrate, and then the particles next to those particles vibrate. In a solid, the particles are very closely packed together, so thermal energy is easily transferred. Once the other solid reached the same temp, they stop transferring energy.

Question 4

Explain convection.

Answer 4

1. A heat source heats up fluid materials which are closest to the heat source. As these materials have a high temperature, they have more KE, which means they are moving away from each other. This results in them having less density
2. As that part of the fluid has less density than other parts, the lighter part will rise, and the denser part will sink to be heated up.
3. This creates a cycle known as a convection cycle.

Question 5

How does a beaker heat up?

Answer 5

1. The heat from the heat source heats up the beaker
2. The beaker heat up the few water molecules in contact via conduction
3. As the water molecules, heat up, the kinetic energy increases and density lowers at that area, as the particles move away from each other.
4. However, the other parts of the water have a higher density, so they sink
5. The water with lower density rises and the water with high density sinks and gets heated
6. This happens till a thermal equilibrium is achieved.
7. This process is known as a ‘convection cycle.’

Question 6

Explain radiation.

Answer 6

1. Radiation is a type of electromagnetic ray which is carried in the form of energy waves. It is the infrared section of the electromagnetic rays
2. The sensation of radiation for a human being is how cold or hot the object is
3. Just like any other energy transfer, radiation move from a high thermal energy zone to a low thermal energy zone. Hence, this can be termed as a method of heat transfer as well.