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# How does the length of the wire affect the resistance.

Extracts from this document...

Introduction

28/11/2002Prashanthini.S

Science Coursework

## PLANNING

### Prediction

I predict that the longer the wire is, the more resistance there would be therefore the less current that would pass through. As voltage is directly proportional to current, I predict that my graph showing the resistance will look like this:

Scientific Explanation

An electric current will flow through an Electrical Component (or device) if there is a voltage across the ends of the component. Resistance is a measure of how hard it is to get a current through a component at a particular voltage. Voltage current and resistance are related by the equation:

VOLTAGE (V) = CURRENT (A) X RESISTANCE (Ω)

Resistance occurs because as electrons pass along a wire they collide with atoms of the metal and so lose energy. The longer the conductor, the more particles there are in the way and so the harder the electrons find it to flow. In a longer wire there will be more collisions and so the electrons will lose even more energy. Other things that alter the resistance are the temperature (higher temperatures mean higher resistance) and cross sectional areas (the greater the area the lower the resistance). The material that the wire is made out of will also have an effect on the resistance.

Middle

45

60

75

90

6 VOLTS

 LENGTH OF WIRE (CM) CURRENT IN AMPS CURRENT IN AMPS AVERAGE RESISTANCE (Ω) 15 30 45 60 75 90

I will repeat the experiment twice and then I will find out the average current. This will make my evidence more accurate. I may have made a mistake whilst conducting the experiment so by repeating the results twice and finding the average, I am obtaining a more accurate result. After finding the average I will use Ohms law to work out the resistance.

Safety

Safety is a very important factor when conducting experiments. If we don’t pay attention to the safety factors that we need to take into consideration, then someone can get hurt quiet seriously. When we are conducting our experiment all of the participants should make sure that we had our safety goggles on. We should roll up our sleeves and those with long hair should tie them back neatly. We must make sure that we don’t have any loose clothing on us. All the books and any unnecessary items should be cleared from the desk. We should make sure that we do not put the crocodile clips any less than 10cm apart. This will lead to an excess of current passing through the wire and consequently the wire will get very hot and start to turn red.

Conclusion

ANALYSIS

From my graph I can tell that as the length of the wire increases the resistance increases with it. This is shown by the steepness of my graph. This experiment goes to show that the length of wire does increase the resistance of it.

The results I have got goes to prove that what I predicted before conducting the experiment was right. I predicted that: the longer the wire is, the more resistance there would be therefore the less current that would pass through. I predicted that my graph would be:

This is exactly what has happened. The graph of results that I predicted is similar to the graph of results containing the figures I obtained whilst conducting the experiment.

Scientific Explanation

Resistance is a measure of how hard it is to get a current through a component at a particular voltage. Voltage current and resistance are related by the equation:

VOLTAGE (V) = CURRENT (A) X RESISTANCE (Ω)

The longer the conductor, the more particles there are in the way and so the harder the electrons find it to flow. In a longer wire there will be more collisions and so the electrons will lose even more energy. Voltage is directly proportional to the current. As a result of this the resistance is proportional to the current.

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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