# Test the resistance of a wire, (nicrome) measured in SWG/mm, to find out if resistance changes as we change the length of the wire.

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Introduction

## Physics CWK

## P- Planning

- Plan basic experiment
- Control variables
- What accurate
- Make prediction (hypothesis) with scientific information.
- Evidence of preliminary work.

Outline Plan

##### In my investigation I will be doing two experiments. The first one will be to test the resistance of a wire when the lengths are altered making sure the area of the wire is kept constant. The second one will be to test the resistance of a wire when the area (diameter) is altered making sure the length of the wire is kept constant. I will have two methods, direct and indirect. The first one (altering the length) I will be using the direct method, where I will be using a multimeter. The second experiment (altering the diameter) I will be using the indirect method, where I will be using an ammeter and voltmeter.

## Aim

-Experiment one - To test the resistance of a wire, (nicrome) measured in SWG/mm, to find out if resistance changes as we change the length of the wire.

-Experiment two – To test the resistance of a wire (nicrome) to see if the resistance changes as we change the area of the wire.

Middle

35.0cm

03.8

03.6

03.6

03.7

45.0cm

04.6

04.6

04.6

04.6

55.0cm

05.7

05.7

05.6

05.7

AREA (with constant length of 20cm)

Diameter (cm) | V1 (volts) | V2 (volts) | V3 (volts) | C1 (amps) | C2 (amps) | C3 (amps) |

0.027 | 0.23 | 0.37 | 0.88 | 0.05 | 0.09 | 0.21 |

0.031 | 0.18 | 0.34 | 0.80 | 0.06 | 0.11 | 0.27 |

0.037 | 0.12 | 0.22 | 0.68 | 0.06 | 0.11 | 0.34 |

0.045 | 0.09 | 0.15 | 0.58 | 0.06 | 0.10 | 0.40 |

0.055 | 0.06 | 0.11 | 0.46 | 0.06 | 0.11 | 0.48 |

*V=Voltage

*C=Current

Calculate resistance…

Conclusion

Graph Three – Resistance over 1/area

As the area increases, the resistance goes down, but not at a steady pace. The graph is curved and in a result is not proportional.

I then plotted a graph of resistance over the inverse of the area to make it proportional. It turned out a straight line therefore proving resistance is inversely proportional to the area.

During my experiment, I did not need to repeat any anomalous results because they were between an acceptable margin of error.

###### E – Evaluation

My experiment went not to badly yet I did struggle with the resistivity. My results came out fairly accurately when I did repeats and came to look at my graphs and final figures.

When averaging out my final results to compare them to the published resistivity, I found one of my final results were very far out. This may hav been because it was the smallest length therefore the current may have been high causing the wire to heat up. When the wire heats up the particles vibrates more. Next time, I will not take readings at 5.0 cm and I will keep the voltage low. I left ths result out when averaging it out

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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