Conduction, Convection & Radiation
St. Patrick’s Comprehensive



Aim:


The aim of this investigation is to find out which material will be the best insulator







Variables:

Cupsize



Lid/No Lid






Water Temp.






Amount Of Water






Room Temp.






Outer Covering







Prediction:


I think the polystyrene cups will work better because the polystyrene is made up plastic that has had air pockets blown into it, this helps keeps heat in because heat cannot travel well over open air particles, and I think the clay mug will be the worst insulator because of it’s large open top.







Method:


We heated some water to 100°C then prepared six cups for testing. We got one plain plastic cup, a polystyrene cup, a glass beaker, a polystyrene cup with a lid and a plastic cup with a lid and a regular 150ml clay cup. We measured the water to the 100 ml level in the beaker and then quickly put the water in the various containers then pressed then timed one minute and took a temperature reading with a thermometer. We did the same for another four minutes then wrote then down in a table. We made this a fair test by using the same amounts of water in each cup, timing it exactly and getting the water from the kettle to the cup as quickly as possible.



Results:


See Separate Sheets



Analysis:





















































Conclusion:
























































I found that the glass plastic and clay mugs are bad conductors, convectors and radiators. I also found that polystyrene is a good insulator, conductor and radiator. The lids help stop heat escaping from the top, this is called convection. The best insulator was the polystyrene cup with a lid, this is not unexpected as is shown in my prediction. Polystyrene is just plastic with tiny air pockets blown into in, this acts as a cell for heat of which it cannot escape, and the lid acts as a further safeguard as that is where the majority of the heat is lost. An advantage of using polystyrene cups is that unlike plastic the heat does not go straight through and burn your hand, it never gets too hot to handle. The worst insulator was the clay cup, this is not because the sides could not contain heat but because the opening is so great at the top, and because cups are coated to keep as much heat/cold in as possible, this just acts as a channel, forcing more heat upwards and out of the cup.


I believe my results are accurate and that I have collected sufficient data to enable me to make that claim. We tried to make the test as fair as possible, although there is still several possible errors that could have affected my results; the time it took to get the boiling water from the kettle into the cup, start the timer and put the thermometer in, you may think that separately each little action took only a fraction of a second, but if you add all the times up you get a large margin for error, the water could have cooled several degrees in that time and although it is only a small amount it still makes the data incorrect nonetheless, my proposed method to overcome this problem would be to add salt to the water, so that it boiled over 100 C, then put it in the cup, add the thermometer and wait until it had dropped to 100 C before starting the stopwatch. Also the room temperature may have increased or decreased between the time of the first and last experiments, this too could have had an effect on the results, to overcome this I think that I could perform each of the tests several times at different times of the day, this would give me and average temperature reading form which I could eliminate anomalous results, and the only other problem I have with the experiment itself is that the cups had been used several times before, I think this could have had an adverse effect on several of the cups, especially the polystyrene, slightly melting it’s inner coating to collapse the air pockets inside, this could be rectified by simply using new clean cups. Although I wish I had more time to get extra results to work out an average, to eliminate