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# How Is Resistance Affected In a Circuit

Extracts from this document...

Introduction

How Is Resistance Affected In a Circuit?

Introduction

For this investigation I will be looking at how resistance is affected in a circuit. There were 4 variables that I could have changed and they are the length, thickness, type and temperature.

Length:         The longer the wire the greater the resistance. This is because when the wire is increased in length it increases the length the electrons have to travel which will slow down the current giving off a greater resistance.

Thickness:        The thicker the wire the smaller the resistance. This is because the thicker the wire the more space there is for electrons to flow through creating a greater current and there for having a smaller resistance.

Type:        The type of wire can affect the size off the resistance as well. There are some wires that are better conductors of electricity than others i.e. copper is a better conductor of electricity than nichrome meaning that nichrome has a greater resistance.

Temperature:           The temperature of the wire affects the resistance. This is because if the wire is hot then the atoms in the wire will vibrate more meaning making it difficult for the electrons to get through as they will keep colliding with the atoms.

Diagram

For my experiment this is a diagram of how the experiment will be set up.

Apparatus

These are the apparatus I will be using for my experiment.

• voltmeter
• ammeter
• ruler
• battery
• power supply
• extra wire
• variable resistor
• connecting wires

Method

This is the method of what I will be doing for the experiment.

1. Set up apparatus as shown in diagram above
2. Make sure the ammeter reads 0.5A (I will explain in the preliminary work)
3. Place the crocodile clip at the beginning of the extra wire (0cm) and move it along 10cm until you get up to 100cm
4. Write down the results for your voltage every 10cm you move the crocodile clip
5. Repeat this until you have recorded from 0cm up to 100 cm

Fair Test

To make a fair test I must:

• Use the same power supply. I must make sure the power supply does not change because it could adjust the current and the flow of electrons either giving a greater or smaller current either way it will result to inaccurate data and it will no longer become a fair test.
• Keep current the same. This is the same reason for the power supply. If the current is changed then it will adjust the flow of electrons giving inaccurate data.
• Make sure I move the crocodile clip 10cm until I get to 100cm. I must make sure I move it exactly 10cm each time to give the most accurate set of results as possible.
• Change only one variable i.e. the thickness of the wire, the type of wire etc I must do this because by changing more than one thing it will stop it from being a fair test and I only want to be focusing on one thing.
• All the equipment except for the wire must be kept the same. I must only change the wire because it is what I am focusing on for this investigation and there wouldn’t be pointless changing anything else as it would not be related to the work at hand and it would not make it a fair test.
• I will also want to repeat the test to get my results as accurate as possible by finding the average of the different results gathered

Middle

0.93

0.93

0.93

0.5

1.86

1.86

1.86

70

1.08

1.08

1.08

0.5

2.16

2.16

2.16

80

1.24

1.23

1.24

0.5

2.46

2.48

2.47

90

1.39

1.39

1.39

0.5

2.78

2.78

2.78

100

1.53

1.53

1.53

0.5

3.06

3.06

3.06

 N.26 LENGTH (CM) VOLTAGE(Volts) CURRENT (Amps) RESISTANCE(Ohms) V1 V2 Average R1 R2 Average 0 0.03 0.01 0.02 0.5 0.06 0.02 0.04 10 0.37 0.36 0.37 0.5 0.74 0.72 0.73 20 0.74 0.71 0.73 0.5 1.48 1.42 1.45 30 0.93 1.07 1.1 0.5 1.86 2.14 2 40 1.51 1.44 1.48 0.5 3.02 2.88 3 50 1.88 1.84 1.86 0.5 3.76 3.68 3.72 60 2.27 2.28 2.23 0.5 4.54 4.56 4.46 70 2.65 2.55 2.97 0.5 5.3 5.1 5.2 80 3.02 2.97 3 0.5 6.04 5.94 6 90 3.4 3.3 3.35 0.5 6.8 6.6 6.7 100 3.75 3.6 3.68 0.5 7.5 7.2 7.36
 N.28 LENGTH (CM)

Conclusion

Improvements that I could have made were to get more types of the wire nichrome so that I could push my investigation further and improve my results giving me a more accurate piece of data. If I wanted to do a different investigation based on the same topic then I could change to one of the variables that I wrote about in the introduction i.e. type of wire, the length of the wire or the temperature of the wire.

I think that my prediction was incorrect because I got confused with how collisions between electrons in a circuit work. Where I said if the wire was thinner then the electrons would travel through faster and therefore creating more collisions in a circuit, I said there would be less resistance where in fact there would be more resistance because the more collisions would cause the electrons to slow down, making the resistance larger. So the thinner the wire i.e. N.26 would have a higher resistance than N.22 because the electrons running through it are moving faster in a thinner wire making more collisions.

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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