• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

To investigate the capacitance and uncertainty of a capacitor.

Extracts from this document...


Fawwaaz Hosein

Name: Fawwaaz Hosein

Group Members: Solmoi Park and Eric Mui

Experiment 3: Capacitor

Date: 5th March 2010

Aim: To investigate the capacitance and uncertainty of a capacitor.


  • Multi-meter
  • Analogue ammeter
  • Resistor
  • Capacitor
  • Battery
  • Switch
  • Connecting wires
  • Stopwatch


  • The circuits are set up as shown in figures 3.1 and 3.2 respectively below.
  • For the circuit shown in figure 3.1, the behaviour on the ammeter when the switch S is closed is described and accounted for. Ensure that a minute or two is allowed to observe the change.
  • The second circuit shown in figure 3.2 is then set up and the behaviour on the ammeter when its position is moved is described and account for.
  • The switch is then closed and the steady current I0 is recorded
  • The switch is then opened and the time for the current (I) to reach particular values is recorded.  
  • The experiment is repeated two more times so as to acquire three sets of time (T1, T2, T3) for the current (I) in question and the average time (t) was also recorded.
  • Using the average time a graph of lnI against t is plotted using the following equation:



Where y= lnI, x= t, gradient = image03.png and lastly y- intercept = lnImax

  • Resistance(R) of uncertainty ±2% is measured using the multi-meter and the Capacitance (C) is found by using the gradient = image03.pngimage04.png
...read more.


































T1 (s)

T2 (s)

T3 (s)

...read more.


From the graph the correlation (R2) between lnI and time was very strong as R2 was found to be 0.99965. As the gradient is negative so to is the correlation, ergo as ln I decreases, Time (t) will increase.


We measured the capacitance of the capacitor and its uncertainty to be: C = (1.23 ± 0.02) mF.

To reduce the uncertainties a digital multi-meter should be used together with data-logging equipment for measuring time to lessen the effect of reaction time when using a stopwatch, ergo increasing the all-round accuracy of the readings.

Using a varying resistors or resistors connected in series in place of the one in question would help in showing a change in resistance, changes the time. Ergo image02.pngwould be observed to remain constant in face of these changes.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

  1. Peer reviewed

    Experiment: Decay of Charge in a Capacitor

    4 star(s)

    Under reasonable range of error, the experiment also shows that the time constant of discharging is equal to the product of the capacitance of capacitor itself and the resistance that it connected across. Also, when two identical capacitors are connected together in series or parallel, their discharge processes still follow an exponential decay.

  2. Investigating the Capacitance of a Parallel-Plate.

    We then investigate the change of current with the change of voltage which is being done by connecting more cells. Results: V / V 1.45 ± 0.05 2.95 ± 0.05 4.4 ± 0.1 5.8 ± 0.1 I / 0.23 ± 0.01 0.47 ± 0.01 0.73 ± 0.01 0.94 ± 0.01

  1. Free essay

    Measurement of capacitance by reed switch.

    * The marked value of the capacitance on the capacitor is not the actual value. * The vibrating switch may not vibrate at the given frequency. * The value of the current cannot be read accurately as the pointer of the micro ammeter is constantly vibrating with a small amplitude.

  2. Investigating the Smoothing Effect of a Capacitor on a Resistive Load

    The flashing trace would occur almost every time the capacitance was changed and required holding the trace each time the readings were made. The focus of the line is important as the thickness of the line can affect the readings when looking at each division.

  1. Resistor - What do resistors do?

    Work through this example again to confirm that you understand how to apply the colour code given by the first three bands. The remaining band is called the TOLERANCE band. This indicates the percentage accuracy of the resistor value. Most carbon film resistors have a gold-coloured tolerance band, indicating that

  2. Write an account of how plants defend themselves against attack by pathogens and parasites.

    Tomatoes also exude compounds that inhibit fungi germination. - Lack of an essential nutrient required by the pathogen - Inhibitory chemicals in plant cells. Resistant potatoes to the common scab disease, Verticillim wilt, contain high levels of chlorogenic acid in their cells.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work