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# Resistance Investigation

Extracts from this document...

Introduction

CHRIS LONGSTER

## Plan

Resistance is the opposition to current and voltage within a given material. George Ohm discovered the concept of resistance in 1826. He stated that the current flowing through a wire is proportional to the potential difference across it as long as the temperature remains constant. The formula to calculate resistance is

Resistance (measured in Ohms)= potential difference across a wire (volts)

Current through a wire (amps)

In this investigation we are going to find out how resistance changes in relationship to when the length of a wire is changed. We will take readings every 10 cm because this should give a substantial variation in the readings and go up to 100 cm because this will give us a sensible set of results to work with. To

Middle

40

0.90

1.29

0.69

50

0.90

1.06

0.85

60

0.96

1.04

0.92

70

1.03

0.98

1.05

80

1.15

0.88

1.31

90

1.18

0.84

1.40

100

1.17

0.81

1.47

 Distance (cm) Voltage (v) Current (a) Resistance (ohms) 10 0.79 1.63 0.48 20 0.90 1.52 0.59 30 0.92 1.31 0.70 40 0.98 1.05 0.93 50 1.02 1.25 0.16 60 1.15 1.09 1.06 70 1.25 1.04 1.20 80 1.38 0.93 1.48 90 1.36 0.88 1.55 100 1.41 0.86 1.64
 Distance (cm) Voltage (v) Current (a) Resistance (ohms) 10 0.78 1.93 0.40 20 0.88 1.59 0.55 30 1.09 1.45 0.75 40 1.30 1.14 1.14 50 1.16 1.12 1.03 60 1.28 1.04 1.23 70 1.06 0.89 1.19 80 1.22 0.95 1.23 90 1.28 0.78 1.64 100 1.29 0.76 1.70
 Distance (cm)

Conclusion

The accuracy of the data was on the whole good but there were two odd results. These were anomalies as the resistance was lower on average than the resistance from the reading taken from a 10 cm shorter wire.

The method for the investigation was well suited to the experiment. To improve the reliability of the results we could keep the room temperature constant, and be more accurate in measuring the length of the wire. We could also use more accurate voltmeters and ammeters.

Due the close position of the points plotted on the graph there is enough accurate information obtained from the results to support the definite conclusion that as the length of the wire increases so does the resistance.

To improve the results we could repeat the experiment but take readings at different or more frequent intervals . We could also take more sets of results.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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