• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7

Investigating The Resistance Of A Light Bulb As The Voltage Is Increased.

Extracts from this document...


Investigating The Resistance Of A Light Bulb As The Voltage Is Increased.

Resistance is the resist of electrons flowing through an electrical component. The resistance slows down flow meaning that the components will heat up due to friction. The current in a circuit gets smaller the bigger the resistance is. To work out resistance you can use this formula Resistance = Volts/Current, R=V/I

To measure the resistance in a circuit you would need to find out what the voltage and the current is in the circuit. To find the voltage of an light bulb in a series circuit and hence the voltage of the circuit you would need to use a voltmeter which would be connect parallel with the light bulb to find the voltage across the bulb (see diagram below). Then you would need to find the current in the series circuit by placing an ammeter in the circuit which would give you the current of the circuit as well as the bulb current (see diagram below) Now you would then divide the volts by the amperes to find the resistance.  

Voltmeter and Ammeter in a circuit diagram


...read more.


Below are the results from the preliminary work and a line graph on the next page shows the results in a line graph.

Voltage (V)

Current (I)

Resistance (Ω)







































Current results 1 in Amperes

Current results 2 in Amperes

Current results 3 in Amperes

...read more.


These results show that if the resistance on the resistance graph is too high it will then be lower on the current graph.

I think that some results are wrong due to the rheostat being unreliable.  One reason for this could have been that the rheostat could have had a loose connection.  Also the coiling of the wire in the rheostat could have become pulled apart with use and this could make the rheostat inaccurate.   I tried to avoid this by checking if any rheostats worked better but they did not work as well. To have solved this the school could have had some new rheostats.

My results were good enough to support the prediction and for this reason I think my investigation was worth carrying out.

Further work to this experiment could have been done with a new reliable rheostat which would give me more accurate results. Also I could have changed the make of the light bulb to see if a different make of light bulb would have given similar results and verified the prediction.  Using a different light bulb may give different results as the metal filament may be different but the general pattern should be the same.

Patrick Pitts

...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. Using an LDR to detect the intensity of plane polarised light allowed through a ...

    light, there was a problem of reflection: Because the ice cream tub was shiny, it reflected light that was scattered by the light bulb. However, there is a way to rectify it. Since I have a calibration curve, I am able to work out the intensity of light for each angle.

  2. Investigating the effect of 'length' on the resistance of a wire

    that gradient can be obtained by calculating the change in the y-axis divided by the change in x-axis. Resistance is on the y-axis and the length is on the x-axis therefore the gradient of the line of best fit is: ?Resistance or ?R/?L ?Length So Gradient = (44.59 - 4.72)

  1. Investigation into the resistance of a filament lamp.

    I will measure the voltage to 3 significant figure, this is because if the voltage of the filament lamp was 12.04 volts then if we were measuring to 2 significant figure then the value would be 12 volts which is not very accurate so therefore it would be precise and accurate to measure the voltage to 3 significant figure.

  2. Sensors cwk. The aim of this coursework is to construct a potential divider circuit ...

    LDR can be used to control the shutter speed on a camera. The LDR would be used the measure the light intensity and the set the camera shutter speed to the appropriate level. Therefore the response time needed for a camera shutter would have to be much faster than the time response of my LDR.

  1. resistivity if a nichrome wire

    = gradient x area (See graph paper) The graph shows a steady increase in the resistivity of the wire, hence, positive correlation. This suggests that there were no anomalous results in my readings as all the points in the graph were flowing.

  2. Free essay

    Resistance of a wire

    This is clearly shown from the positive correlation line in the graph with a fixed gradient. From my results on the averaged results graph you can clearly see that there 2 anomalies. EVALUATION After finishing my experiment and looking over my method and how I worked out certain things, I

  1. How different factors affect the resistance of a wire

    SWG 32 Length / cm Voltage / V Current / A 20 0.73 3.01 40 0.61 4.34 60 0.45 5.05 80 0.35 5.42 100 0.29 5.54 I have decided to use Nickel Chrome, SWG 32 as it seems to be the least dangerous wire to use and also provides me

  2. Choosing a light source

    This is because some of the lights were being absorbed only allowing certain colours to go through (reflecting out); depending on which light source you're looking at. And also some of them (the colours) were close but not close enough like natural light.

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