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

Objective To investigate the relationship between the charge on a capacitor and the p.d. across the capacitor by charging at a constant rate.

Extracts from this document...


880810.doc        p./


Ng Wah Catholic Secondary school




Tang Pak Lap        ( 19  )


AL Physics


7th May 2007



C8  Charging a capacitor at a constant rate (TAS)


To investigate the relationship between the charge on a capacitor and the p.d.

...read more.


CROConnecting leads


  1. Connect the following circuit. Set the CRO to d.c. and the sensitivity to 1 Vcm
  2. Set the time base of the CRO to a high sweep rate so that a steady horizontal trace is displayed. Shift the trace to the bottom of the screen.
  3. Short out the capacitor by connecting a connecting wire across it (XY). Adjust the 100 kΩ potentiometer to a suitable value for a steady current to flow (e.g. 80μA).
  4. Remove the shorting wire and the capacitor will charge up.
  5. Repeat the
...read more.


Sources of errors

  1. Error in keeping the current constant
  2. Internal resistance of the cell
  3. Non-zero value of the variable resistance when it is "minimum"


The microammeter reading is being decreased and the CRO trace is being increased when the shorting lead removed. It can be deduce that as the capacitor discharges, the p.d. across it decreases.

A-Level Practical Physics (Third Edition)© Oxford University Press 2005

...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)

    When connected in parallel, the time constant , the discharge rate is halved compared to a capacitor alone. Experimental Hypothesis Hypothesis: The discharge current follows equations or . C. Experimental Design Apparatus: Multimeter, 0-50�A (work as ammeter) Voltmeter, 0-5V 3 x 1.5V battery Electrolytic capacitor 470�F, 50V x 2 Resistor 100k?

  2. Investigating the Capacitance of a Parallel-Plate.

    We can find the relative permittivity of a dielectric, which is compared with the permittivity in vacuum. We setup the parallel-plate capacitor with 3 layers of spacers and connect it to 4 batteries, i.e. 5.8 V as displayed by the voltmeter.

  1. Characteristics of Ohmic and Non Ohmic Conductors.

    The circuit is shown below The connecting wires are joined onto the supply. The circuit is thus set up as shown above. The following table can be drawn Thermistor For this the voltage will be constant. However voltage can be listed in the table to calculate the resistance.

  2. To investigate the capacitance and uncertainty of a capacitor.

    * Circuit 2 (Main CR circuit), Figure 3.2: When the switch was closed the current was observed to remain at 60?A as the capacitor was charged to its maximum. Immediately after the switch was opened the reading (A) on the ammeter began decreasing.

  1. Charging a capacitor at a constant rate

    It shows that the p.d across the capacitor is directly proportional to the time. When the time increases, the p.d across the capacitor increases linearly. Discussion: * When the capacitor is charging up, the current decreases with time.

  2. Plotting the decay curve of charge in a capacitor

    The readings were tabulated. 6. A graph of the charge Q against time was plotted. It was called the decay curve of the charge in the capacitor. B. Measurement of discharging current by a microammeter 7. The circuit as shown in Fig.2 was connected.

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

    There are two categories under which errors can be regarded as; systematic errors and random errors. Systematic errors occur often when there are faults in the apparatus i.e calibration faults and zeroing of the apparatus. Random errors are also called human errors and are a result of the experimenter's technique.

  2. Physics - Rotary Potentiometer

    Another item to take in consideration is how accurate the calibration is, after the experiment I intend to use 100g weights to repeat the experiment and compare to see the difference in voltage readings. This will enable to me to see how accurate and consistent the readings are.

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