The temperature of the object is well approximated with the kinetic energy of the substances. The high temperature means that the molecules within the object are moving at a faster rate.
But the question arises, how to measure it? Molecules in any substance are very small to analyze and calculate its movement (Kinetic energy) in order to measure its temperature. You must use an indirect method to measure the kinetic energy of the molecules of a substance.
We studied that solids expands when heat is supplied to it. Like solid substances, liquids are also affected by heat. To know this let us do the activity 1.
In a thermometer, when liquid gets heat, it expands and when it is cooled down, it contracts. It is used to measure temperature.
Like solid and liquid objects, the effect of heat is also observed on gaseous objects.
What is required?
A small glass bottle, a rubber cork, an empty refill, water, colour, a candle, a fork, a paper.
What to do?
• Take a small glass bottle. Fill it with coloured water.
• Make hole at the centre of the rubber cork.
• Pass empty refill from the hole of the rubber cork.
• Make the bottle air tight and observe the water raised in the refill.
• Make a scale on paper, place it behind the refill and note down the position of the surface of water.
• Hold bottle with fork and supply heat to it with candle. Then observe.
What is the change in the surface of water?
The surface of water level rises up.
• Stop the supply of heat. When water is cooled, observe the surface of water in the refill, what change takes place? Why?
The surface of water level goes down because water contracts when it is cooled.
When, a liquid is heated, it expands and when it is cooled down, it contracts.