To explore how the efficiency of a kettle changes with the volume of water that is used to heat it.

Liam Derbyshire

GCSE Investigation: Exploring The Efficiency Of A Kettle

Aim:

Prediction:

Through a kettle heat is lost through mainly three areas. Firstly, through radiation, this is when heat is thrown out of the kettle via the kettle wall out of the main body of water. The second way is by conduction, this is where heat passes through the main body of water via the kettle wall. And, also by convection, where some of the water particles carrying energy are lost through water vapour through the spout of the kettle. In all these ways of heat loss, everything revolves around the surface area, where all the heat is lost. The bigger the surface area of the volume of water, the more heat energy will be lost.

I have done some preliminary work, which proves that if the volume of the body of water doubles, the surface area is unproportional to the body of water even though you would expect it to double. I have looked at the effects of changing the volume of water and calculated its surface area through the expression 2 πr(r+h). I am treating the kettle as a cylinder. As the kettle has a volume of 0.5 litres of water, the surface area is 387 cm2, at 1.0 litres of water, the surface area is 528 cm2, which demonstrates that doubling the volume does not actually double the surface area.

Preliminary Calculations

Preliminary Calculations:

Method

Firstly, set up the equipment. In this experiment I am timing to see how long it takes to heat water of given temperatures. I will then fill the kettle up with 500ml of tap water, measuring the water accurately in a measuring cylinder. I will then put the temperature probe in to the kettle at approximately 1cm away from the heating element and ensure that in all my experiments I keep the probe the same distance away from the element because otherwise the temperature of the water will vary throughout the ...