Convection Currents Made Simple



When a part of liquid or gasoline is heated it expands and turns into much less dense. The hotter, much less dense liquid rises upwards and cooler liquid falls to take its place. This cycle of a liquid or gasoline rising and falling is known as a convection present.

We arrange a quite simple convection present demonstration utilizing cold and warm water with meals colouring to point out the motion of heat water by way of chilly water.

Convection Present Demonstration

You’ll want

Tall glass or vase

A smaller glass or cup

Scorching water

Chilly water

Meals colouring

Warm coloured water in a small container in a larger jar of cold water to show warm water rises


Fill the tall glass or jar with chilly water.

Fill the smaller container with sizzling ( however not boiling water ) and add a couple of drops of meals colouring.

Fastidiously place the small container into the container with the chilly water.

Watch what occurs to the hotter, colored water.

The recent, colored water rises upwards and collects on the high of the chilly water. It then cools and sinks downwards. Finally all of the water would be the similar temperature.

How does convection work?

Particles of heat water transfer extra rapidly and unfold out. They rise upwards by way of denser cooler water which sinks to the underside the place it warms up. Finally all of the liquid is similar temperature.

The nice and cozy water rises as when liquids and gases are heated they increase. This implies they take up extra room however have the identical mass so their density is lower than when they’re cool. Substances with decrease densities float on substances with larger densities.

Diagram showing water heating in a pan and the direction of heating. Warmer water rises, cooler water falls to take its place. This cooler water is then heated and rises.
Convection present in heated water

Ask an grownup to assist with this exercise

Further Problem

Repeat the exercise with chilly water as a substitute of sizzling and watch what occurs to the colored water.

cold water in cold water for a science experiment about convection

How is warmth transferred?

Warmth will be transferred in three other ways. Conduction, convection and radiation.


Conduction of warmth happens when vibrating particles cross any additional vibrational vitality to close by particles. The extra vitality the particles have, the warmer the thing will get. An instance of this kind of warmth switch is when steel pans are heated on a hob. Warmth travels by way of the pan. If the pan deal with can be steel, it’ll get sizzling too. This is the reason steel pans typically have plastic or picket coverings on their handles. Plastic and steel are usually not good conductors of warmth.


Convection of warmth is when hotter molecules of a liquid or gasoline transfer from a hotter to a cooler space taking the warmth with them.

Water being heated in a pan is an instance of convection. That is the kind of warmth switch we demonstrated above.


Radiation of warmth is when warmth is radiated to the encircling space by warmth waves. Particles are usually not concerned in this type of warmth switch.

Warmth from the solar travelling by way of area is an instance of warmth switch by radiation. One of these warmth is transferred by waves.

Diagram showing convection, conduction and radiation with the example of a camp fire
Diagram exhibiting conduction, convection and conduction

Within the campfire and pan instance above all three sorts of warmth switch will be seen.

Warmth travels by radiation from the camp hearth to the steel pan. Warmth travels by way of the steel of the pan by conduction to heat the decrease layers of water. The water is then heated by convection because the much less dense hotter water rises by way of the cooler water to create a convection present!

Bear in mind – warmth is barely transferred is there’s a temperature distinction.

Science ideas

  • Density
  • Conduction
  • Convection
  • Radiation
  • Warmth switch

Final Up to date on June 13, 2022 by Emma Vanstone



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