1.4 Convection
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Convection currents in water when heated by a Bunsen burner.
Convection is when more energetic particles (those particles that are hotter) moves from cooler regions to warmer regions and take their energy (heat) with them. The warmer particles take the place of cooler particles. Convection only occurs in liquids and gases. Convection cannot occur in solids because the particles in solids are in a fixed position.
Liquid and gases expand when they are heated. This is because the particles in hot water have more energy and therefore take up more room. This results in hot water being less dense than cold water and this causes hot water to rise upwards. Cooler water is denser and therefore falls to the bottom of the container. These movements in particles are known as convection currents.
Liquid and gases expand when they are heated. This is because the particles in hot water have more energy and therefore take up more room. This results in hot water being less dense than cold water and this causes hot water to rise upwards. Cooler water is denser and therefore falls to the bottom of the container. These movements in particles are known as convection currents.
Convection currents in water when heated by a coil that is situated in the water.
Suppose we have a particle that is near the heat source (which in this example is a radiator). The radiator transfers heat to this particle. This particle is now warm, meaning it has more energy and therefore become less dense. As the particle is less dense, it starts to rise. As the particles rise, they start to lose (heat) energy by passing on energy to other particles. A loss of heat energy causes the particles to vibrate less resulting in them becoming denser, causing them to sink. The cooler particles move back to the heat source where they receive more energy and the cycle starts again.
If we were looking at convection currents in water with a coil heating up the water, we would only have convection currents above the water source because the water below the heat source stays cold because there is almost no conduction.
If we were looking at convection currents in water with a coil heating up the water, we would only have convection currents above the water source because the water below the heat source stays cold because there is almost no conduction.
As air is heated it becomes less dense and therefore rises above the denser cooler air. This is why hot air balloons rise.