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Does the resistance of an electrical wire depend on its length?

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Introduction

Does the resistance of an electrical wire depend on its length?

        An investigation was carried out to answer the question, Does the resistance of an electrical wire depend on its length?.

To answer this I will watch an experiment and us the results to prove whether or not resistance of wire depends on its length.

For this experiment the equipments used are, 1m length of nichrome wire which is a copper alloy, a voltmeter an ammeter, crocodile clips and a battery pack. When the equipment was set up the voltage and current were recorded with different lengths.

           Metals are good conductors of electricity. This is because in metals, there are free electrons to move between the positive ions which are arranged in a regular lattice, if a

Voltage is applied across a length of a wire this will give the electrons increased energy and push them in the same direction, causing a current to flow.

Resistance is caused by electrons colliding with a stationery positive ion. Resistance blocks current and so a greater resistance means a reduced current. A material with high resistance is one in which the positive ions keep restricting the progress of the electrons.

...read more.

Middle

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          Form previous work it was discovered that the voltage across a wire is directly proportional through it. In other words, if the voltage is increased the current is increased while resistance remains constant, as long as the wire does not get hotter. However from my investigation we are going to find out if the resistance of the circuit will or not change if the length of one of the wire is increased.

My hypothesis is therefore that, if you increase the length of one of the wires you also increase the resistance, because there is more stationery positive ions, therefore restricting the progress of the electrons, because the electrons collide with more of the stationery positive ions, this then slows down the electrons and reduces current. Therefore making resistance to be greater.

Analysis

Length m

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Current, I (amps)

3.32

2.65

2.17

2.13

1.67

1.45

1.44

1.32

1.21

1.21

Voltage, V (volts)

0.60

1.04

1.39

1.60

1.80

1.96

2.11

2.19

2.29

2.39

Resistance,  R

0.18

0.40

0.64

0.75

1.08

1.35

1.47

1.66

1.89

1.94

Resistance =

voltage, V          

Current, I

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Conclusion

I could have done some further work such as ?

Using a different wire, pure copper, this is because it contains more ions

It is a transition metal, which makes a good conductor of electricity.

Also I could have otherwise completely changed the whole investigation to see the effect of cross sectional area on the resistance, the same length will be cut from reels of constantan and manganine wire which have different diameter. The results will show that if a is the cross sectional area, R  l/a.

{The area is   , whereby r is the radius, or         which is       where d is the diameter.}

Which I predict will be, the thicker the wire the lower the resistance of a given length. If the diameter is doubled the resistance decrease to one quarter, of its original value for the same length of wire.

...read more.

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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