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  • Level: GCSE
  • Subject: Science
  • Document length: 3411 words

What Factors Affect the Resistance of an Electrical Conductor?

Extracts from this document...

Introduction

Leanne Heath 10 Derby 1 What Factors Affect the Resistance of an Electrical Conductor. The key factor I am going to investigate is what affect different lengths of wire has on the resistance of the wire. Hypothesis Resistance is the force which opposes the flow of electrons through an electrical conductor. Resistance occurs when the negatively charged electrons travelling along the current in the wire collide with the positively charged atoms of the wire. Hence the atoms are the property which opposes the flow of electrons. These collisions slow down the flow electrons, causing resistance. The electrons have to try to avoid, or travel around the atoms, therefore the flow of current is slowed down. The amount, size and density of atoms have an effect on resistance. The circuit itself holds some resistance. There are 3 factors which can affect resistance. These are : * The material of the wire * The length of the wire * The diameter of the wire The material of the wire is a very important factor. Different wires contain different numbers of atoms. Some wires have lots of atoms, whereas others have few atoms. A wire that does not easily conduct electricity would be said to be a bad conductor of electricity. An example of a metal conductor that does not easily conduct electricity is called nichrome. Wires that have many atoms will have a high resistance compared to wires which have a few atoms which have a low resistance. Wires have a high resistance because there is a smaller area for the electrons to pass through, because there are a large number of atoms present in the wire. Large numbers of atoms reduce the amount of area for the electrons to pass through. Also the size of these atoms can change. Some atoms are large compared to others which are small. A wire which large atoms will have a high resistance because there will be a small area for the flow of electrons in the current to pass through.

Middle

Therefore when of the ice has melted and become a liquid the temperature rises. That's why the investigation has to be stopped when all of the ice has melted. To stop the wire touching I will place insulation tape around the wire as it is being wrapped around the test tube. This will stop the wire from moving around which means that the wire will not touch and short out. Safety To make sure that this investigation is safe the following aspects should be taken into account: * Don't touch the wire and the boiling tube just after the investigation has been done because the wire will still be hot. * Don't use faulty wires or a faulty power pack. Method The method that I will use in this investigation is 1. Collect the apparatus and check that all of the apparatus is working. 2. Set up the apparatus 3. Set the power pack to 4. (This means that the voltage won't be too high) 4. Place 40cm of new wire around the boiling tube, checking that none of the wire is touching as this will decrease the length of the wire. 5. Position the insulation tape around the wire. 6. Put the ice inside test tube and seal with a bung. 7. Turn on power pack, ammeter and voltmeter. 8. Push switch so that the current flows into the circuit. 9. Take first reading from the voltmeter and ammeter. 10. Repeat reading. 11. Find the average of both readings. 12. Record results in a table 13. Adjust the variable resistor to increase the current. 14. Repeat what has previously been done. 15. Adjust the variable resistor three more times. 16. Repeat for 50 cm, 60cm, 80cm, and 100cm. 17. Plot a graph of results and draw a line of best fit. Below is a labelled diagram of the experiment: Variable Battery Resistor Switch Voltmeter Ammeter Wire Boiling Tube Constantia Wire Ice Prediction Using my scientific knowledge on resistance I can make a prediction.

Conclusion

This therefore would reduce the resistance of the wire because the current would take the easies route, which is the shortest instead of taking the longest route around the coil. This means that there would have been less collisions between the atoms of the wire and the electrons of the current. Therefore the current would have flowed faster than expected. Also as the electrons wouldn't have had as far to travel as predicted they wouldn't have had to squeeze together for as long, meaning there would have been less collisions between electrons and other electrons. The 60cm wire could have already been used. This means that it could have still held an electrical charge which would increase the resistance of the wire. Also all of the ice in the boiling tube could have melted meaning that the temperature would have increased, resulting in the resistance being increased. If I could repeat the investigation again there would be a number of changes that I would make. One of these changes would to decrease the lengths of the wire. The 100cm wire was too long and it was difficult to wrap the wire around the boiling tube without any of the coils touching. Also I could have used a bigger boiling tube that had a wider diameter. It would be easier to wrap the wire around the boiling tube without any of the coils touching. Also if more repetitions were done there would be less chance of anomalous results appearing. If I did the experiment again I would change the ice after each experiment. Therefore none of the ice would melt completely and the temperature wouldn't rise I don't think that the voltmeter and ammeter were read incorrectly because there are no massive changes in the two reading on the table. If I was to repeat the investigation I would make sure that the wire was new wire that hadn't been previously used and that the wire came from the same strip. I wouldn't change my graph because I fell that it is clear and easy to see where each length of wire is.

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