conduction and convection

Where does conduction mainly occur and convection only occur in?

Conduction mainly occurs in solids- hear is transferred through convection for solids

Convection only occurs in fluids so both liquids and gases - heat is transferred by convection in fluids

What is conduction

The process where Vibrating particles transfer energy to neighbouring particles

Why does conduction occur mainly in solids

Because the particles in a solid are held together really closely which means there’s a lot of collisions that pass on the energy. Whereas liquids and gases the particles are further apart and so they don’t collide as much.

What is thermal conductivity

How well objects transfer energy by conduction is known as their thermal conductivity

A measure of how quick energy is transferred through a material in this way

give example of what has a high and what has a low thermal conductivity and what does a high thermal conductivity show

Metals I have a high thermal conductivity and transfer heat energy rapidly. Materials with a high conductivity transfer energy between the particles quickly.

Plastics have a low thermal conductivity, which is why they are used as insulators and almost all fluids have a low thermal conductivity

Where can convection happen in

Gases and liquids

Why does convection occur in fluids

Because the particles in fluid aren’t fixed once heated and gain kinetic energy they all move around faster by the process of random diffusion. This will cause the more energetic particles to move away from the warmer region towards the cooler region and overall this means that the higher energy particles in the warmer region are a lot more spread out than those in the cooler region. So fluid in warmer region actually expands as it heats up and become less dense than the cooler fluid

How is convection current created

Bc liquids and gasses can flow the warmer less dense regions will rise above denser cooler regions if there is a constant heat source convection current can be created

More detailed explanation of convection current form in fluids

If you had a container of fluid as we heat the container first, the particles near the heat source would gain kinetic energy and spread out becoming less dense. Because they are less dense these particles rise above the colder less dense particles above them and at the same time cooler particles sink down and take their place whilst this is happening The hot particles will lose their energy and cool down and the cool particles now at the bottom will heat up because of this cycle will keep repeating for as a long as the fluid is being heated we call this a cycle a convection current

Where do we see convection currents

In radiators in buildings

In oceans

How do we reduce convection

Stop the free flow of fluids

What do conduction and convection both have in common

Involve particles gaining kinetic energy but in conduction only the energy transferred and in convection the particles move