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

Find how changing the amount of voltage (potential difference) coming out of the power pack will affect the current while it is flowing through a filament bulb of 24W.

Extracts from this document...

Introduction

Physics Coursework

Filament Bulbs

Aim:

My aim is to find how changing the amount of voltage (potential difference) coming out of the power pack will affect the current while it is flowing through a filament bulb of 24W.

Diagram:

image00.png

image19.pngimage09.pngimage18.png

image04.png

image20.png

image21.pngimage04.png

image02.pngimage01.png

image03.pngimage04.png

image01.pngimage02.pngimage05.png

The power pack supplies a direct current (DC) to the circuit. The voltmeter is in parallel to measure the potential difference across the bulb and the ammeter is in series to measure the current flowing through the circuit.

image06.png

Method:

  1. Get all the equipment and set it up as shown in the diagram.
  2. Set power pack so that the voltage shows 10V on the voltmeter.
  3. Record the number of amps that are flowing through the circuit by reading the ammeter.
  4. Repeat steps 2 + 3 for 20, 30, 40 and 50 Volts.
  5. Repeat the steps 2 through 4 two more times to get three sets of results. Make an average and this leaves you with a set of good, accurate results.

Fair Test:

...read more.

Middle

image08.pngimage07.png

The graph shows that the voltage goes up in proportion to how much current there is. But I predict that the resistance of the bulb will not change throughout the experiment.

However as the filament is used for a longer period of time, the filament inside the bulb will get hotter.

How resistance is caused:image13.png

It is stated in the particle theory that as molecules and atoms are heated, they will begin to vibrate. Its vibration will cause the resistance to increase by scattering the electrons so that less electrons can get through.

image14.png

image15.png

image15.png

image15.pngimage17.pngimage15.pngimage17.pngimage17.pngimage15.pngimage15.pngimage17.pngimage17.pngimage16.pngimage17.pngimage17.pngimage15.pngimage15.pngimage17.pngimage15.pngimage15.pngimage17.png

So the hotter the filament gets, the higher the resistance. In theory, this should cause the light bulb to slowly stop increasing in current due to the resistance, as shown in the graph below.

image12.png

...read more.

Conclusion

th or 5th) we get a trend line which represents the data more accurately.

Results Graph 02:image23.png

This graph shows that the resistance is going up in a complex way. This could be because the temperature is not rising in a steady manner. This will affect the amount of resistance as we know that resistance is linked to temperature. This could be one explanation for having a complex shape curve. Another explanation for having points outside the trend line is that there could be experimental error (eg. Not reading the ammeter correctly).

Evaluation:

        I think this experiment went very well as I got the results I had expected. I executed the experiment very well as I did a very fair test, I did everything I mentioned in my fair test section.

        However, there was an anomaly in my data, I think this is down to human and equipment error as the equipment is not 100% accurate.

        All in all this was a successful experiment as I got the results I needed, analyzed them and found out what I wanted to know.

...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. Relationship between the current and voltage.

    I believe this, as no light will be given off, even though there is some resistance in the circuit. This is, as the bulb needs a certain amount of activation energy. Before it lights up. Once the bulb has been lit up, there will be a steep gradient for a while, and then the gradient will decrease.

  2. How the resistance of a filament bulb varies its current flowing through it

    I plan to do my experiment with 5 bulbs to make it fair. However as I can see I don't think I will have enough time to get it done therefore I will only do it for 2 to 3 bulbs.

  1. How Does Voltage Affect Current

    the line joining the plotted points together on the graph was a straight, diagonally upward, line. So my prediction is that the current and voltage will increase equally meaning the graph we produce this time will show a steady increase of both voltage and current, forming a straight diagonally upward line.

  2. Assess how changing the electric current in the electrolysis of acidified water affects the ...

    In my prediction, I stated that I thought that the increase in the rate of hydrogen production would be directly proportional to the increase in current. My result and graphs clearly show that this is indeed the case and that the two are directly proportional.

  1. To prove ohms' law, and to study the relationship between current and potential difference ...

    x: y2 - y1/x2 - x1 = 4.4 - 0 / 0.36 - 0 = 12.2? * Resistance in y: y2 - y1/x2 - x1 = 4 - 0 / 0.39 - 0 = 10.3? * Resistance in z: y2 - y1/x2 - x1 = 2.2 - 0 / 0.42 - 0 = 5.2?

  2. Investigating the factors affecting the size of current flowing through a length of resistivity ...

    that all the factors are the same except for the cross-sectional area of the putty. If you look at the figures in italics you will see that when the cross sectional area is quartered from 4cm2 to 1cm2, the current is also quartered from 0.26A to 0.064A.

  1. Find The Internal Resistance Of A Power Supply

    The digital ammeter and voltmeter were very sensitive and the fluctuating power supply (direct current) and they were very sensitive to these very small fluctuations in current, and as a result, the values being displayed were fluctuating. The procedure I used enabled me to repeat the experiment, which I did

  2. 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

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