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

The aim of this experiment is to find how resistance changes in a circuit containing bulbs in series or parallel and how they are related.

Extracts from this document...


Physics Coursework                                                                        James Taylor 11MA

An Investigation of Resistors

In Series and Parallel


The aim of this experiment is to find how resistance changes in a circuit containing bulbs in series or parallel and how they are related.

For this experiment I will need knowledge of electricity and physics. A famous physicist Ohm made an important discovery. Known as Ohms law, from his discovery he stated that: ‘the current flowing through a conductor is directly proportional to the potential difference across its ends provided that the temperature is constant’. In equation form this is: R = V/I. From his discovery we are know able to work out the resistance of a circuit from knowing the voltage across the circuit and the current flowing (amps). After his discovery the units with which we measure resistance were named after him – Ohms, the symbol for which is the Greek letter omega (Ω).


In this experiment to investigate the resistance of light bulbs in series and parallel there are a number of variables, which I could change or keep the same. The dependent variable, which I will change is the voltage across the circuit, I am able to change this using a variable resistor.

...read more.




Circuit Type

Ohms Resistance (Ω)

1 Series


2 Series


2 Parallel


On the whole this smaller experiment proves my prediction. As shown in the results table the two bulbs in series provides double the resistance of one bulb in series. While the circuit with the two bulbs in parallel is halve the resistance than that of the one bulb in series circuit.


Firstly I will set up the equipment for the experiments in series. I will start of with the voltage on the power pack set to twelve volts. I will then add one bulb to the circuit. I will use the variable resistor to find the reading of 0.6 amps flowing through the circuit. I will then record the voltage across the bulbs. Increasing the amperage each time till I reach 1.3 amps. I shall then redo the experiment three times so I can work out an average reading and also to ensure accurate results. I shall then increase the number of bulbs to two in series and do the experiment again. Then I will do the same for two bulbs connected in parallel.

The independent variables in this experiment will be:

  • The current flowing through the circuit, which I will be able to change using a variable resistor.
  • The number of bulbs used.
  • Whether the resistors are in series or parallel.

The variables I will be keeping constant in this experiment are:

  • A voltage of 12V flowing through the circuit.
  • The type of wires used.
  • The types of bulbs used
...read more.



Overall I think the experiment was carried out exceptionally well with very few errors. Also I did not record any unusual readings due to the fact that I checked the circuit was connected properly and I let the results stabilise before I took a reading. However, because I used non-ohmic bulbs there was a slight curve on the graph, this could have an effect on the reliability of my results. This could be avoided next time by using a set of ohmic bulbs to avoid getting the heating up and cooling curves on the resistance graph. From the results I am able to state a definite conclusion, which supported my prediction. My prediction stated, two resistors in series would double the resistance the current is held through each one and that two resistors in parallel should halve because the current is split between the resistors, through my results this is fully supported. However, I could extend the investigation I could add more bulbs in series and parallel circuits to see if it still follows the pattern I discovered in this experiment. For example if I used three bulbs in series and parallel would it mean that they would be three times as big and a third of the control.

...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. Thermistor Coursework

    Although the potential difference output from the lab pack fluctuated, I corrected this as best as I could before every reading was taken. The potential difference was correct to one hundred millivolts of the total output. The 1000 ohm variable resistor that I used actually was 996 ohms when I measured it after the experiment.

  2. Investigating the E.m.f and Internal Resistance of 2 cells on different circuit Structures.

    + (1/R + 1/r) 1/r + 1/r = it is also equal to internal resistance in series with one cell 1/r + 1/r = it is also 1/2 of the internal resistance of a series circuit with two cells Using experimental data I can justify my conclusion: The series circuit with two cells: Internal

  1. Single Phase Transformer (Experiment) Report.

    The calculations have proved to me that the equivalent circuit method has worked, enabling me to predict the results of a transformer and effects with certain loads. * Now to predict the voltage regulation and efficiency if the load used above had a power factor of 0.8 lagging.

  2. The aim of my investigation is to determine the specific heat capacity of aluminium.

    This may make my results nearer the book values. Oil was placed in the hole in the aluminium block, which contained the thermometer, to speed up convection current between the block and the thermometer so that the heat is transferred quicker. Convection occurs quicker in oil due to the fact that the particles in the oil are closer together

  1. physics sensor coursework

    This may produce some problems when producing a calibration graph, because a simple equation cannot be derived. Deriving an equation We can convert the graph from a curve into a straight line by using a logarithmic scale instead of a linear scale: Light intensity/ lux Resistance/ ohms Log light intensity Log resistance 0 12212.96 #NUM!

  2. Characteristics of Ohmic and Non-Ohmic Conductors.

    These conditions apply to all metallic conductors. Therefore, a thick, short piece of copper will offer negligible resistance when compared with a long copper wire. This is because it is much easier for the electrons in the copper to move through a greater area and the smoother the flow of electrons, the larger the current.

  1. Investigation into the resistance of a filament lamp.

    11.71 8.50 1.52 12.89 9.00 1.56 14.07 9.50 1.60 15.17 10.0 1.63 16.27 10.5 1.71 17.96 11.0 1.75 19.25 11.5 1.79 20.62 12.0 1.88 22.60 Voltage(volts) Temperature (Celsius) Temperature (Kelvin) 0.50 125� C 398 1.00 250� C 523 1.50 375� C 648 2.00 500� C 773 2.50 650� C 923

  2. Characteristics of Ohmic and Non Ohmic Conductors.

    If correct accurate reading regarding the current and the voltage has to be taken, then the ammeter is connected in series and the voltmeter in parallel. This way we will know how much current is flowing through the circuit if the object is a conductor.

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