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Does a Light Bulb Obey Ohm's Law?

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Introduction

Does a Light Bulb Obey Ohm's Law? Obtaining Table of Results Voltage 1 Current 1 Voltage 2 Current 2 Average Voltage Average Current Average Resistance 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.5 0.37 0.5 0.38 0.5 0.375 1.33 1.0 0.56 1.0 0.55 1.0 0.555 1.80 1.5 0.63 1.5 0.64 1.5 0.635 2.36 2.0 0.72 2.0 0.72 2.0 0.72 2.78 2.5 0.75 2.5 0.74 2.5 0.745 3.36 3.0 0.85 3.0 0.86 3.0 0.855 3.51 3.5 0.90 3.5 0.91 3.5 0.905 3.87 4.0 0.98 4.0 0.99 4.0 0.985 4.06 4.5 1.04 4.5 1.04 4.5 1.04 4.33 5.0 1.09 5.0 1.10 5.0 1.095 4.57 5.5 1.17 5.5 1.17 5.5 1.17 4.70 6.0 1.23 6.0 1.24 6.0 1.235 4.86 6.5 1.27 6.5 1.27 6.5 1.27 5.12 7.0 1.30 7.0 1.31 7.0 1.305 5.36 7.5 1.39 7.5 1.39 7.5 1.39 5.40 8.0 1.42 8.0 1.43 8.0 1.425 5.61 8.5 1.45 8.5 1.46 8.5 1.455 5.84 9.0 1.48 9.0 1.48 9.0 1.48 6.08 9.5 1.56 9.5 1.57 9.5 1.565 6.07 10.0 1.59 10.0 1.60 10.0 1.595 6.27 10.5 1.62 10.5 1.63 ...read more.

Middle

The smaller the cross section of a wire, the more struggle for electrons to go past, the greater the resistance * Wire Material. Different materials conduct electricity in different ways, the better the conductor, the less the resistance. The worse the conductor, the more resistance. * The same light bulb, which had the same tungsten filament. Ohm's law does not apply to circuits where there are temperature changes. The variable, temperature, meant that ohm's law could not be applied to the light bulb. It is the light bulb itself that emits the heat. It's source is the tungsten filament, as when electrons try to pass through the tungsten filament they collide with the tungsten atoms which induce heat and increase the atoms' vibration, which leads to further collisions and leads to more light heat and of course resistance. The result supports my Hypothesis. Evaluation I believe the investigation was successful as the results produced agree with scientific knowledge. ...read more.

Conclusion

Voltage was supplied with an accurate variable d.c. supply. Current was measured using an accurate ammeter and voltage was measured with an accurate voltmeter. For further accuracy I conducted the experiment twice so I could work out the average. Both times the results were expected and were very similar. Therefore I believe that this investigation has sufficient evidence to support a conclusion that a bulb does not obey ohms law. A bulb is a non ohmic conductor. If I were to repeat the investigation I would improve it by * Using other conductors like lasers. * Made the length of the wire into a an independent variable * Made the cross section area of the wire into an independent variable * Made the material of the wire into an independent variable * Made the type of bulb into an independent variable Although I believe my investigation to be a success I believe if I were to make the improvements I said, I would have reliable results with an even stronger conclusion as a wider range of information would have been taken into account Ohm's Law 1 Stepney Green School 10548 ...read more.

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