| Resistance Of A Wire Essay, Research Paper
I am conducting
this experiment to determine how a certain variable affects the resistance of a
piece of wire in a circuit. PLANNINGSafety To make the experiment safe I will: ·
Make sure the wire is not connected for long periods of
time. This makes the wire hot and destroys equipment. ·
Disconnect the wires should the ammeter reading go too
high.PredictionI predict that as the length of wire increases the
resistance will increase. This is because the electrons have further to travel
and lose energy. Equipment·
Power supply (0 ? 10v) ·
Ammeter (0 ? 5 Amps) ·
Digital voltmeter ·
Crocodile clips (x3) ·
Meter ruler ·
Nichrome wire (I metre) ·
Leads/connectors (x7) ·
Variable resistor Possible Variables ·
Length of wire ·
Voltage ·
Temperature of wire ·
Current flowing through wire ·
Width of wire ·
Type of wire (copper, steel etc) ·
Equipment in use (leads rheostat)To make the experiment a fair test I will vary only one
thing- the length of the wire. The current and voltage stay the same. The wire
will stay the same except for length. I will use nichrome wire in my circuit.I am going to measure the voltage from 10 cm to 100 cm in
10 cm increments. I will repeat the experiment 3 times in order to gain an
average result and use Ohm?s law to calculate the resistance.RESULTS TABLE Length
of wire 1 Voltage 2 3 Average
volts (V) Resistance R=V/I (W) 0 0 0 0 0 0 10 0.35 0.33 0.35 0.34 0.17 20 0.65 0.65 0.66 0.65 0.33 30 0.99 0.98 0.97 0.98 0.49 40 1.3 1.4 1.3 1.3 0.65 50 1.66 1.65 1.67 1.66 0.83 60 1.98 1.98 1.99 1.98 0.99 70 2.29 2.29 2.27 2.28 1.14 80 2.65 2.64 2.65 2.65 1.33 90 2.97 2.95 2.96 2.96 1.48 100 3.28 3.29 3.30 3.29 1.65 ANALYSIS AND CONCLUSIONSFrom my graph I can see that the straight line indicates
that the length of the wire is proportional to the resistance.As the length of the wire was increased the resistance
also increases. This is because the current is made up of electrons. The
electrons lose energy the further they have to travel. Also, as the wire gets
hotter, the resistance increases because the atoms in the wire vibrate more and
this makes it difficult for the electrons to pass through the wire.I can now say that my prediction ?as the length of the
wire increases the resistance will increase? is supported by my results. EVALUATION I obtained my results by setting up the circuit show in
the diagram on the previous page. I moved the crocodile clips in 10 cm
increments and read the voltage off the digital voltmeter. I repeated the
experiment twice more and then calculated an average voltage. I then calculated
the resistance by dividing the current (2 amps) by the average voltage. This
method of calculating resistance is known as Ohm?s Law.From my graph, I can see that my results were accurate.
All the points are very close or on the line of best fit in a positive
correlation. There were no anomalous results.?As I obtained
accurate results, I think that the method I used was suitable. However, there are certain improvements I could make to
improve the accuracy, namely:·
Making sure the wire is straight so measurements could be
taken accurately. ·
Making the wire straight would enable more accurate
positioning of the crocodile clips, which again would give more accurate
results. ·
Letting the wire cool down sufficiently in between
readings. When the wire heats up, it has lots of energy, which causes the atoms
in it to vibrate, making it harder for the electrons to travel. This increases
the resistance via another method, so it is not a truly fair test.?As I have
previously stated, my results have a good standard of accuracy. This is shown
by the points being near or on the line of best fit and there were no anomalous
results. Therefore my results support a firm conclusion that the length of wire
is proportional to the resistance.
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