# Does The Resistance Rate Depend On How

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 ·

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 equipment was

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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