Investigating Capacitors - page 7
Keywords: Investigating Capacitors coursework GCSE physics
By slashwk on 23/11/2006 17:28:09
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 7 of 9 pages: 1 2 3 4 5 6 7 8 9
was some evidence which questioned this statement, which is explored in more depth below).
The first thing one notices about the graphs is their striking resemblance to one another in an exponential curve shape. This firstly proves my theory of having this type of curve due to the fact that in each and every capacitor, no matter what the voltage in the circuit was, the same issue was present with the repelling electrons. As I mentioned in my hypothesis, the process is very simple. The negative electrons travel from one terminal of the power supply and reach the first plate. As there is no full circuit, all the electrons pile up onto the one plate. As like charges repel (i.e. positive repels positive, negative repels negative), this causes for any electrons coming from the cell to find it difficult to get onto the plate as time goes on (and more and more electrons get onto the plate). This builds up quite a big repulsion against negative electrons. As metals have a ‘sea’ of free electrons, this repulsion get so strong that it starts repelling electrons which are on the opposite plate. This force gives them enough push to push all the way around the circuit and back to the cell. This therefore gives the rather clever illusion that there is a full circuit in which electrons are flowing, but this is obviously not the case. We can see through evidence and scientific theory that my first hypothesis was correct, and also that for that reason my second hypothesis was also correct.
I have also noticed some further points that I may wish to investigate. Experiment 1 and experiment 5 are exactly the same except that experiment 1 uses 3 volts, and experiment 5 uses 6 volts. What interests me is that they both took the same length of time to (almost fully) charge. As well as this, it looks like experiment 5’s capacitor charged up twice as quickly as experiment 1’s. This is all great evidence which could easily be stated as: double the voltage, and the capacitor will charge at double the speed in order to finish charging at the same time (therefore the voltage would have not effect on how long the capacitor took to charge to the full). But this is not likely to be the case because no other experiments had the same correlation between the experiments involving
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