Physics Project Plan Essay Research Paper Physics

Physics Project Plan Essay, Research Paper

Physics Project The Planning Key V A ..... Variable

resistor .......

Ammeter........ Light bulb....... Voltmeter ........ I am carrying out an experiment to

find the different resistances created by a light bulb at different

temperatures and currents. Because of the nature of a light bulb, it glows

white-hot when fully on, the resistance will change at different currents. When

the current is low and the bulb is not very bright, it won.t be as hot and

therefore it will have less resistance. But when the current is high and the

bulb is brighter, it will have a high temperature and high resistance. I will

be using the following circuit for the experiment:Definitions Ammeter

. This is a device that measures the current of electrons in Amps. It has to be

placed in series on the circuit. Voltmeter

. This is a device for measuring the potential difference of the electrons in

the circuit. They are measured in Volts. It is placed in parallel. Variable

Resistor . Also called the Pecometer it acts in the same way as a normal

resistor, to resist the current, but this one can have a variable resistance. ........ To use the circuit, I will take

readings from both the ammeter and the Voltmeter, when the variable resistor is

in different positions. I will need to try and get results that are high and

ones that are low, and try to have an even distance between each result. I will

take down the readings from both the ammeter and the voltmeter. I should end up

with 30 results, hopefully all evenly spaced. ........ The resistance is greater when the

light bulb is hotter, because when any material is heated, the atoms making up

that material vibrate over a larger distance more than they usually do. This

vibration of atoms can get in the way of passing electrons and therefore

results in fewer electrons getting through and a higher resistance. Also,

though the reason that the filament in the light bulb heats up and glows is

because the electrons passing by at a normal speed will still knock into atoms.

Although it is not as frequent as at high temperatures, the electrons will

cause the atom to vibrate. This is the action, which causes the heating of the

filament. Above

is a diagram of how electrons move around the material. This

process wastes quite a lot of energy, because as the current increases, the

resistance increases. This .waste of energy. can be greatly made up for by

using super conductors, which are conductors that are super cooled. This would

save energy but it then would not work for a light bulb, as the whole purpose

of a light bulb is to create a resistance to make a light. ........ To measure the

resistance for different power levels I will be using the .Standard Test

Circuit.. This includes a voltmeter to measure the voltage around the bulb, an

ammeter to measure the current, a variable resistor to make measurements of

different currents, and the actual light bulb. ........ For the experiment, the

ideal amount of results is thousands, but because of the restraints of the accuracy

in the classroom and the time period, I will be working with about 30 results,

across different currents. This should let me do enough results to draw a firm

conclusion, but will be within any time constraints. ........ There is a basic,

commonly used graph of an ideal lamp, showing the relationship of current and

voltage. The graph below is it. V This graph shows the ideal pattern of results for the

experiment, but because we are working in a classroom environment, there are

many factors such as minor room temperature fluctuations, contamination.s in

the wiring materials, non-accurate measuring instruments and a non-accurate

power supply. All the above factors could be improved upon to give more

accurate and true results, but this would be quite unpractical on the level

that we are doing the experiment for GCSE.s Obtaining Evidence ....... ..........

For this experiment I will be using a circuit called a Standard Test Circuit.

It has a variable resistor, a light bulb, a voltmeter, an ammeter, and the

power supply. A diagram of the circuit is below. V (volts) I (amps) R (ohms) V (volts) I (amps) R (ohms) 0.03 0.02 1.5 1.23 0.16 7.69 0.04 0.03 1.33 1.38 0.17 8.12 0.06 0.04 1.5 1.63 0.18 9.06 0.07 0.05 1.4 1.87 0.19 9.84 0.09 0.06 1.5 2.01 0.20 10.05 0.10 0.07 1.43 2.2 0.21 10.48 0.15 0.08 1.86 2.37 0.22 10.77 0.23 0.09 2.56 2.6 0.23 11.30 0.37 0.10 3.7 2.86 0.24 11.92 0.52 0.11 4.73 3.1 0.25 12.4 0.71 0.12 5.92 3.37 0.26 12.96 0.82 0.13 6.31 3.58 0.27 13.26 1.03 0.14 7.36 3.82 0.28 13.64 1.15 0.15 7.67 4.24 0.29 14.62 4.44 0.30 14.8 ........ Using

this test circuit, I worked by finding out the voltage for every 0.01 Amps.

This was OK until I started getting very low and I found I had to use 4

variable resistors, all on full power with only one cell to reach 0.02A. Below

is a table of results that I gained

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