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Investigating the Resistance of Wire.

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Introduction

Investigating the Resistance of Wire In this investigation, we are investigating how the length of wire affects resistance current and voltage. We can change the size or number of cell(s), the length or thickness of the wire, and the length of the circuit. To do this, we will set up a circuit: A cell connected to an ammeter and a piece of wire in series, and a voltmeter connected outside the circuit (so that the voltage and current will not change due to their presence. For this experiment we will be using a 6V cell, wires to connect the circuit, an ammeter to measure current, a voltmeter to measure the voltage, and the wire we are measuring the resistance of (Constantine). This means we will be measuring current (in amps) and voltage (in volts), from which we can work out the resistance (in ohms). The range of results we will be collecting will be from 1m to 10cm of wire, measuring every 10cm. ...read more.

Middle

This means Resistance equals voltage divided by current. The results are shown below: Test 1: Length Of Wire (cm) Voltage (V) Current (A) Resistance (Ohms) 100 3 0.6 5.00 90 2.8 0.64 4.37 80 2.6 0.7 3.72 70 2.5 0.72 3.41 60 2.4 0.82 3.30 50 2 0.9 2.44 40 1.8 0.98 1.60 30 1.5 1.20 1.54 20 1.2 1.3 1.00 10 0.8 1.38 0.62 Test 2: Length Of Wire (cm) Voltage (V) Current (A) Resistance (Ohms) 100 3 0.6 5.00 90 2.8 0.64 4.37 80 2.7 0.7 3.85 70 2.5 0.76 3.29 60 2.4 0.8 3.00 50 2.2 0.9 2.40 40 2 1 2.00 30 1.8 1.2 1.50 20 1.5 1.4 1.07 10 0.9 1.7 0.50 Test 3: Length Of Wire (cm) Voltage (V) Current (A) Resistance (Ohms) 100 3.2 0.68 5.30 90 3.1 0.7 4.43 80 3 0.78 3.85 70 2.9 0.82 3.54 60 2.6 0.94 2.77 50 2.4 1.1 2.19 40 2.2 1.3 1.69 30 1.9 1.5 1.27 20 1.5 1.6 0.93 10 1.2 1.8 0.60 From this we worked out the average resistance of each length of wire (by adding all the resistance values for that length of wire and dividing by three): Length Of Wire (cm) ...read more.

Conclusion

The evidence we have is good quality, was directly proportional to a good quality extent, but wasn't totally accurate (most resistance values are a small amount of an ohm off direct proportion). The main anomaly appears to be the metre value, since the resistance is quite far under direct proportion. It is .11 under what it should be for 1M, and so are a few other values, this could be down to a battery not fully charged; it isn't too inaccurate though. Our procedure was good too, but more repeats could have been done to make sure it was a fair test. On the other hand, more repeats could have made the data less accurate due to almost all the results being slightly inaccurate. The evidence we have collected is sufficient to support our theory, and although we do have one large anomaly and a few small ones, we also have a few perfect examples of direct proportion. To provide extra evidence, more repeats could have been done, and an extra experiment on different types of wires, seeing how the material affects resistance. Overall it was a good and accurate experiment. Ralph Weatherburn 11T ...read more.

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