Much Constantan Wire Is In The Circuit? Essay, Research Paper
Aim The aim of this experiment is to
investigate or find out how the resistance of a wire is affected by different
lengths. How the length of a constantan wire affects its resistance. Prediction Constantan is a malleable alloy of nominally 60% copper and
40% nickel. I should expect to see the resistance level rise, as the
length of the constantan wire gets longer. I think this because the more wire
there is for the electricity to pass through the more ions it has to pass. I
expect to see a fixed relationship between the four variables. Apparatus ·
Ammeter ·
Voltmeter ·
Power Pack ·
2 Crocodile clips ·
Wire cutter ·
Constantan wire ·
Meter rulerMethod ·
Cut out 10 pieces of constantan wire
measuring 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, and 100cm. ·
Set up the equipment using the diagram ·
Place the constantan wire between the two
crocodile clips ·
Turn on the mains ·
Read out and record the first reading the
ammeter and volt meter gives ·
Repeat this for all the lengths of wire
taking three sets of readings for each length.Variables ·
Length of wire ·
Voltage ·
Current Diagram ? Safety
Issues We
carried out the experiment with great caution. No protective equipme
necessary. The power pack reduced the mains voltage to a safe level for
working. We kept the working area tidy and dry, to avoid short circuiting. Results and graph. (See separate sheets attached.) The experiment was carried
out on two separate days the first three readings were taken on the first day
and the remainder on the second with a different set of apparatus. This may
explain the anomalous step in the graph between the reading taken at 3 and 4
centimeters. From the results table it
can be seen that some inconsistent readings were obtained from both the
voltmeter and the ammeter, this was maybe because there was a fault in the
equipment or possibly a poor connection. However when calculating the average
of the three readings the ones that were obviously wrong were ignored.Conclusion On each day a clear trend
was established, the resistance increased in direct proportion to the length of
wire. I would expect the resistance to be zero for zero length of wire. The
formula for a straight line is y=mx+c where ?m? is the gradient and ?c? is the
intercept. With ?c? equal to zero the formula becomes y=mx or in this case
r=ml. In this particular case
however the accuracy of the results is not sufficient to prove this absolutely.
To make this a more accurate experiment I would use equipment that showed no
inconsistent readings. ?? Sources of information: www.ohmslaw.com
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