The aim of this investigation is to study capacitors charging and discharging. A capacitor is charged by placing it in a circuit with a resistor and a power source
Capacitor investigation report Eleanor hood
Aim: the aim of this investigation is to study capacitors charging and discharging.
A capacitor is charged by placing it in a circuit with a resistor and a power source. When electrons flow round the circuit they can not cross the gap the capacator makes. A negative charge builds up on this side of the capacitor whilst on the other a positive charge because of this. A potential difference across the gap now occurs causing the charging to slow down. When the voltage across the gap is equal to the voltage of the power supply there is no current as there is no voltage difference/ potential difference and the capacator is now fully charged. A capacitor can then be used in a circuit on its own with out a power source the charge of the capacitor gradually leaves it, and is discharging.
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In This experiment we charged a 1000μF capacitor and then discharged it using two circuits. We studied the capacitor charging by using a voltmeter in parallel and a 10kΩ resistor in series. Every 5 seconds the voltage was taking down, we then repeated this process but with the capacitor discharging.
These were the circuits used:
And these were are results:
These were the graphs:
From these graphs we can that the charge is building up gradually and is curved, with the charge slowly levelling off Because of the relationship with the potential difference changing across the capacitor. When looking at the discharging graph we can see an exponential curve; this can be certified by looking at the natural ln graph of the discharging graph we can see that it gives a linear pattern.
This shows that it is exponentially discharging, and from previous knowledge I know that it is following the equation V=V0e-t/RC V= voltage and R= resistor C= capacitor. Looking at Trend line of the graph we can see that the graph is not following the trend completely we can also see that there is also an extreme anomaly in the results with the second to last point.
By Looking a the graphs and the result we can see that the experiment went to plan however there are anomalies which can be seen in how the trend line fits the ln graph and in certain areas of the graphs. These were most likely because of human errors in taking the reading at the wrong time or misreading the voltmeter.
When looking a the results the discharging begins at 10 v but the charging ends a t 11.25v, the capacitor was not fully charged when
Discharging. However this did not greatly impact the experiment as we can still see the exponential example that we wanted.
Improvements however can be made to the experiment n that we could have a voltmeter with a better degree of accuracy i.e. more decimal places on the reading, with a computer recording the voltages instead of a human. We could also repeat the experiment and take an average of the results recorded this would give us more accurate graph.
To conclude it can be seen that the capacitor charges gradually because of the potential difference across the gap with in the capacitor. We also know that discharges exponentially and that an equation can be used to determine different voltages at different times during the discharging process.