Demonstrating Transfer of Heat in Liquids- Grade 5

Materials

●   Sawdust

●   A glass container

●   A stand

●   Water

●   A matchbox

●   A source of heat (a candle)

Procedure

a.   Fill in the glass container with water

b.   Place a small amount of sawdust in the water

c.   Allow the sawdust to settle at the bottom of the container

d.   Place the glass container on the stand

e.   Heat the container using candle as the source of heat

f.   Observe what happens.

As the water continues to heat, a steady rise of sawdust is observed. This is because the water at the bottom of the glass container gets hotter, expands and rises.

The cold water at the top then moves downwards and takes the place of the risen hot water.

The cycle repeats itself. The sawdust particles show a movement in the water called convection currents. Therefore, heat is transferred in liquids through convection.

TRANSFER OF HEAT IN GASES

Demonstrating transfer of heat in gases

Materials

• A small carton box with a top

• Hard paper or piece of carton

• A piece of paper

• A short candle

• A match Box

Procedure 

1. Make a chimney on each end of the top of the box

2. Divide the box with hard paper or a piece of carton to make two chambers A and B. place the transparent glass on the side of the box for viewing.

3. Light up a candle. Put the lit candle below the chimney B on the box. Close the box.

4. Place a burning piece of paper over chimney A as shown in figure 6

5. Observe chimney B and tell what you see.

6. Record your observations.

Observation

1. The burning paper produces smoke that moves from chamber A to Chamber B through the opening.

2. The candle in chamber b heats the smoke coming from chamber A, which becomes lighter and rises.

3. As the smoke rises up it moves up through chimney B. Cooler air enters Chamber A through chimney A, creating a circular motion known as convection currents.

4. These currents can be viewed through the transparent glass. The transfer of heat in gases is known as Convection

   

Application of convection in everyday life

Convection of heat is used in everyday life by many ways.

These ways include:

1. Ventilating buildings

2. Inflation of hot air balloons

3. Heating of food in a microwave

4. Formation of land and sea breezes

5. Boiling of water in a sufuria or kettle

6. Vehicle engines

Transfer of heat by radiation

When you stand in the sunlight, you can feel the warmth of the sun. The heat energy from the sun is transferred to your skin through radiation.

When you sit beside a fire, you feel warm. The warmth of the heat from the fire is transferred from the fire to you through radiation.

Application of radiation in everyday life

Radiation is used in everyday life in many ways. These ways include:

1. Warming ourselves using electric heaters

2. Using solar heaters in the house

3. Drying clothes and grains

4. Using greenhouses to aid growth of plants

Project

Making an improvised solar heater.