What is the different between convection and radiation?

Answer 1

The three main ways of transferring heat between objects are Radiation, Convection and Conduction.

Conduction - Can be either transfer of heat or of electricity. Particles must be touching for heat or electricity to travel through them. Materials that conduct well, are called conductors. Materials that do not conduct well are called insulators.

Radiation - When an object is heated it emits infra-red radiation, an electro-magnetic wave of wavelength 0.7 and 300 micrometers. Infra-red rays can't be seen by the human eye, but behave in a similar way to light. Dark rough objects absorb the most infra-red, where as light shiny objects reflect the most. When an object absorbs infra-red radiation it is heated. Infra-red radiation does not to move through a substance, it is most efficient in transferring heat when moving through a vacuum, as no heat is lost due to being absorbed by particles.

Convection - Is how heat moves around a fluid (a liquid or gas). A heat source (such the fire under a pan) heats the fluid by conduction or radiation. Then as the temperature of the heated particles in the fluid rises their density decreases. An particle will experience up thrust when it's density is less than it's surroundings. As such the heated particles will rise above the cooler ones, and the cooler ones will fall. In the example of the pan full of water on a fire the heat source is at bottom, so when the cooler water falls it is heated more meaning that it rises again. This means that the particles in the fluid move in a cycle. So the heat moves through the fluid by convection.

Answer 2

convection is heat transfer through non-contact. radiation is heat transfer through space. like the sun.

Answer 3

Convection involves movement of matter. Radiation means that the energy is transferred through electromagnetic waves.