Question

Which best decribes the process of radiation

Answer 1

What's the answer

Answer 2

We are talking about energy transfer here.

Conduction is the process of transfer in solids and happens because the outer electrons of the molecules become energised and detached from their original molecules and pass on that energy to other molecules. It is a relatively slow process.

Convection happens in fluids (liquids, gases and gels for example) and happens because the fluid near the heat source becomes hot and expands and so becomes less dense. It is then more buoyant than the surrounding cooler fluid and so is forced upwards away from the heat source, taking the heat with it. As it rises in the fluid it cools down and so becomes more dense and then sinks once more towards the heat source. It is a faster process than conduction.

Radiation is the heat transfer method that can take place in a vacuum, although it can take place in a material medium. A hot body produces energy that is beyond the red end of the visual spectrum. It travels at about 300 000 km/sec. The hotter a body is the more energy it radiates. We can easily feel the radiated energy of the sun on a clear day.