Investigating Capacitors - page 5
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: 5 of 9 pages: 1 2 3 4 5 6 7 8 9as if the capacitor is not charging, but in fact it is (this should be represented by a straight line on any graphs that we will produce from our obtained information). Therefore I can predict that our graphs are most likely to be exponential (as the line has to cross the y-axis due to starting voltage and time both being 0.0).
Method
In order to find out how much time a capacitor takes to charge in relation to the voltage it is receiving, I need to be able to vary some aspects of my experiments in order to get sufficient information to support any theories. I will obviously have to vary the voltage. I can do this by changing the amount of voltage going into the circuit via a power supply, or I can insert a resistor into the circuit in order to change the total amount of voltage present in the circuit. Also, in order to create even more variability, I can vary the type of capacitor I am using. I need to assemble a circuit in which I can see how the voltage across the capacitor that I am analysing is varying with time, and therefore I will also require a stopwatch to be able to take down readings during intervals. I have decided to use a 10kΩ resistor and a 100kΩ resistor specifically because one is ten times more resistive than the other. I am not sure, but this may be able to produce interesting results for us to use as correlations will be easier to spot. Therefore, I have decided to use the following apparatus:
Power Supply
Wires
Crocodile clips
Voltmeter
10kΩ resistor
100kΩ resistor
1000µF capacitor
2200µF capacitor
Stopwatch
I will use these components to assemble the circuit below:
1. First of all I will set up the equipment as shown (note that I have to put the capacitor in the correct way or it may explode!)
2. Then after that I will make sure that the capacitor is fully discharged by touching a wire to the terminals on the capacitor
3. Then I will turn on the voltage at the same time as someone starting the stopwatch.
4. We observe how quickly it is charging in order to decide whether to take intervals every 5 or 10 seconds (rather like how a chemist would carry out a titration by letting the acid run without measuring in order to find roughly where the indicator changes colour)
5. After deciding how long our intervals are going to
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