• 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 ...

    follow the same shape as the ideal results, however, are slightly less sensitive. I think one of the reasons for this stems from the problem of ambient light. In my initial plan, I talked about using an ice cream tub to block ambient light, and while it blocked some ambient

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

    ?m Resistivity and the area of cross-section are both constant for the wire used which is why the line has a fixed gradient. The length and the resistance increased in a steady fashion, we can therefore say that the resistance of the wire is directly proportional to its length.

  1. Investigation into the resistance of a filament lamp.

    Zero on the Kelvin scale is considered the be absolute zero; that is, the point at which all molecular motion stops. (http://www.usatoday.com/weather/wtempcf.htm) Few ways to measure the temperature of filament lamp > You could measure the wavelength of the light emitted from the filament lamp > You could use the

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

    Evaluation As a whole I think this coursework went well as I meet my aim of constructing a potential divider circuit which could be used in either streetlamps or as a curtain opener/closure. I believe that the results I obtained where accurate to certain extend, however I do believe there were errors which might have slightly affected the results.

  1. resistivity if a nichrome wire

    = gradient x area ? = (16.2 ? m-1 ) X (7.07 x 10 -8 m) = 115 x 10 -8 ? m The real resistivity of nichrome wire is: 110 � 10-8 ? m My value for the resistivity of the nichrome wire is 116 x 10 -8 ?

  2. Free essay

    Resistance of a wire

    Looking back on the final experiment we did, the crocodile clips were not as accurate as they could have been in measuring precisely the distances. Also, I don't think that we left the wires for 30seconds between each reading due to time restrictions.

  1. How different factors affect the resistance of a wire

    with the most data, because it loses heat the fastest, preventing the wire from becoming too hot too quickly and therefore interrupting the present resistance in the circuit. Extent and Range As I have decided that my independent variable for this investigation is the length of wire, I am going

  2. Choosing a light source

    I could now say that, natural light forms all the rainbow colours from red to violet and they are all very close together (closely attached together). Whereas the other light sources only gave out certain colours i.e. some of them were giving out one or fewer colours (look at these lights sodium, the red coloured bulb and the mercury).

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