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Find out how the length of the wire affects its resistance.

Extracts from this document...

Introduction

Hayley Thorpe    10F            Science       Course Work               (Resistance)

Science Coursework.

Aim:

I want to find out how the length of the wire affects its resistance.

Method:

  1. Set up the circuit with the... cm wire
  2. Switch on the power supply
  3. read the voltage across the wire, and the current
  4. Change the length of wire x to 40cm, 60cm, 80cm, and 100cm
  5. Read the voltage and current
  6. Record voltage and current in results table.

Factors:

The factors are:

  • The current
  • Length of wire
  • Voltage across the wire
  • Power Supply

The factor which I will change will be the length of the wire, because I want to know how the length of the wire changes the resistance. Additionally I will be measuring the wire. The factors that I will be controlling would be the power Supply to find the Current the equation is I=V/R

  • I= The Current
  • V= The voltage
  • R=The resistance

The factors I will keep the same are:

  • The type of metal being used, I will make sure that only copper wire is being used.
  • The cross sectional area of the wire, I will make sure that this stays the same by making sure the same wire is being used all the time.
  • The temperature of the wire-I will keep the current the same, this will ensure that the wire does not overheat. I will take 3 readings from each of the lengths and then use the average to put into my results table... Resistance will be calculated by voltage/current. I will make sure that the wire or any other component gets too hot by keeping safe levels of current
...read more.

Middle

Apparatus:

  • The apparatus which I will have to use are:        image09.png
  • Crocodile clipsimage02.png
  • Voltmeterimage02.png

image10.png

  • Ammeterimage02.pngimage11.jpg
  • Rulerimage02.pngimage12.jpg
  • Connecting wiresimage02.pngimage13.jpg
  • Power Supplyimage02.png

image14.jpg

You’re Experiment:

Before I start the experiment the teacher will check it. I will pass a current through a piece of wire, the wire carries a resistance, and this causes the electrons to hit the atoms. I can test how the resistance changes in the different wire lengths; I will increase the voltage to ensure that the current is kept the same. I will not change anything apart from the length of the wire from 10cm to 100cm. I made a record of the current and potential difference, via the voltmeter and the ammeter. My results are reliable as I did the experiment three times. Every time the readings were similar proving that there was no mistake in collecting the results.

My results could have been more exact if more accurate instruments were used. Unnecessary loss of heat within the connecting leads may have been a factor affecting accuracy. 

Diagram:

image15.png

Safety:

  • Make sure hands are dry.
  • Be careful when handling wires they might get hot.
  • Do not let the wire get to hot or it will burn.
  • In order to perform a safe experiment, a low voltage of 2V was chosen so that overheating was minimilised.
  • Before switching on the power ensures that the circuit is complete.
  • Students work in small groups, so that every thing is under control.
...read more.

Conclusion

My method was suitable as I got the results I wanted, the experiment could be repeated on a larger scale to make less room for error think that better equipment would have given more precise results.

To improve the experiment, the clips could be attached more carefully; a more accurate ammeter would make sure that the current is always exactly the same. A better voltmeter would have given better resistance results. The wires and clips used would also have an effect on the resistance; the wires could be insulated better to reduce heat loss. The results would then contain no anomalies. The above would definitely produce better events.

  • You could compare resistance to a high street. If you walk down one street and bump into a certain amount of people, in a street twice the length you are likely to bump into twice that certain amount of people. It is in this way that resistance works.

During this experiment I have found out many things such as:

  • The resistance of a wire depends on its thickness
  • The thinner the wire, the higher it’s resistance
  • You must use thick wire to carry a large current or the wire will get too hot and melt.

...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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