Lab Report on Energy

Anton Johansson, 9E

2. The Light Bulb and the Plates


2.1 Planning

2.1.1 Description of Lab

The second lab on thermal energy was to understand how fast light emitted thermal energy to objects around – in this case three plates of different colour.

                      The light bulb is to be placed in the middle of the three plates – one silvery, one black and one white – from the same length (10 centimeter). On the back of every plate, we will have taped a thermometer. We will then turn the light bulb on, and every minute (starting when we have just turned the light bulb on, recording this as after 0 minutes) check the temperature and note this down so we later can analyse the results.

                      As soon as we are convinced that the plates have reached their top temperature, we will turn the light bulb off and analyse the drop of temperature for a while.


2.1.2 Equipment and Materials Needed for Lab

·           Nearby electricity for the light bulb

·           Light bulb

·           Timer

·           Holder for the three plates

·           Three thermometers (and tape)

·           Pen and paper for noting results etcetera


2.1.3 Diagram of the Equipment’s Set Up

See page 3.


2.1.4 Hypothesis

I believe that the three will begin on about the same temperature (experience tells me that there’s always an error making one start on one degree higher or lower because of for example miscalculation, bad measuring on the length between the light bulb and the plates, etcetera), and have their temperatures increased steadily. I think that the black plate’s temperature will increase faster, as black is a colour that easier attracts thermal energy. As silver reflects thermal energy more, I think the silvery plate will not be as affected. The white will probably stand somewhere in the middle, as I’m not familiar with anything special about that colour (associated with thermal energy).

Of course we have to consider that everything works totally correct for having these results. The main impact on the results is probably bad timing – if someone is late checking the temperature or similar. As explained earlier, there’s always something that goes wrong. It can also be that we measure wrongly and that one of the plates is to far away from the light bulb, resulting in temperature increasing slower. There’s not really a way to avoid these errors but to be extra careful – check everything twice.


2.2 Performance & Conclusion

2.2.1 Results

See page 4 and 5.


2.2.2 Conclusions

All three of the plates turned out quite similar (as expected). At first, both the silvery and the black started at 21 degrees Celsius and the white started on 22 (probably because of an error, see section 2.1.4 for more information). After four minutes, all three of them had somehow gotten to 24 degrees. After six minutes, we turned off the light bulb, so a few minutes after that the temperature started to decrease. All of them were on different numbers when we stopped the lab, after five minutes; silver on 22, black on 21 and white on 23.

                      I had expected the silvery plate to be much less affected, but still it actually increased and decreased much quicker than the white, which I had expected more so of. Though, as expected, this was the one who didn’t warm up as much as the others (as I had expected),

                      The black plate was the most reactive to the thermal energy, quickly raising in temperature and reaching the highest in the middle – 25 – as well as the lowest in the end – 21. This was expected in my hypothesis, as I already knew how attracting black is. In the end (minute 12-14) it jumped from 21 to 22 degrees, and then back to 21. This is for an unknown reason that I cannot understand at all. Probably it was just a miscalculation, or minor changes in wind, room temperature or similar.

                      The white plate truly was the most boring one. As already pointed out, it started on 22 degrees for an unknown reason. It then was the only one to only jump one degree for the first minute. It stayed on 23 for one minute, and then changed into 24 to stay there for seven minutes, then turning back into 23 for the rest of the time. White took the role that I thought silver would have, being barely effected by the thermal energy at all – only taking skips of one degree at the time, without having time to cool down to less than 23 degrees before we finished the lab.

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