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

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

Extracts from this document...

Introduction

Neil Fraser        Science        Mr Fox

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

Plan

Resistance is the confrontation of electrons flowing through an electrical component. The resistance slows down the flow through the component, due to the friction created. The current in a circuit gets smaller the bigger the resistance is.

To work out resistance you can use this formula:

  Ohm’s Law – R= V           (Resistance = Voltage/ Current)

                                                             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 a light bulb in a series circuit and hence the voltage of the circuit you would need to use a voltmeter, which would be connected in 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.)

To find the resistance of the circuit, you would then divide the voltage by the current.

For this experiment I will be using a series circuit rather than a parallel circuit.

...read more.

Middle

The diagram below shows inside a piece of wire showing the free electrons-the flow- and the metal ions. If the temperature is increased then the free electrons in the diagram will hit the metal ions more creating more resistance. If the thickness of the wire was changed i.e. when the metal is thinner the free electrons will have a smaller area to pass through and will hit the metal ions more and so there is greater resistance, than in a thicker wire where there is a greater area for the electrons to pass through. Therefore it will be easier for the free electrons to move through a thicker wire and the resistance is therefore lower.

I believe that if the Voltage and/or the current are increased then the light bulb filament will get brighter and the resistance will go up because the temperature changes. This breaks ohms law as the temperature changes so therefore the resistance will change. You can tell that the temperature rises because of the colour of the light bulb filament. If the light bulb filament is an orange colour at around 2 volts

...read more.

Conclusion

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.

...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 ...

    for the other resistor, we can work out the value we expect for the voltage: The reason for the 1000000(25cos2(a)) is as our approximation gives us a value of k?, so we needed it to be just in ohms. This formula produces a graph looking something like this: My results

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

    Gradient = 54.84 ?/m If we re-arrange the resistivity formula we will see that: Resistance = R e s i s t i v i t y Length Cross-sectional area Anomalous Results From The Graph Of Average Results: From my results, I can prove the uncertainty by making use of the resistance formula.

  1. Investigation into the resistance of a filament lamp.

    This in-rush current requirement should be taken into account in the selection of the power source for a specific lamp application. (Gilway.com) Converting between Celsius and Kelvin: You can convert between Celsius and Kelvin like this: Kelvin = Celsius + 273.15 Scientists use the Kelvin scale, which is based on the Celsius scale, but has no negative numbers.

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

    The method I used to carry out this experiment and obtain the results could have distorted the final accuracy of the data. One of the main problems, encountered when trying to obtain the results was fixing the light bulb at the same height as the LDR.

  1. resistivity if a nichrome wire

    Table of errors (absolute/ percentage errors) Length (meters) Average voltage (volts) Current absolute error (amps) Current percentage error (%) Voltage absolute error Voltage percentage error (%) 0.100 0.001 0.37 0.240.01 0.24 4.17 % 0.37 0.015 0.37 4.05 0.200 0.001 0.75 0.240.01 0.24 4.17 % 0.75 0.01 0.75 1.33 0.300 0.001

  2. Free essay

    Resistance of a wire

    This I feel has had a negative impact on some of our results has they had to be collected over two separate sessions. We kept the same power pack but the wires were mixed and most likely causing different wires to be used.

  1. How different factors affect the resistance of a wire

    to use lengths of wires ranging from 20cm long to 100cm, as this will give me a large enough range to obtain sufficient results for my conclusion. It will be harder to go over 100cm as then two rulers will have to be put next to each other, and this is not at all reliable.

  2. Choosing a light source

    were close but not close enough like natural light. TASK 3: In this task I am going to research how a spectrometer and a diffraction grating can be used to determine the wavelength of light sources. This is a spectrometer The sorts of reads you need to take or have are: 1. sin ? (which represents the angle i.e.

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