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What factors affect the resistance of Ni-Chrome wire?

Extracts from this document...

Introduction

What factors affect the resistance of Ni-Chrome wire?

Hypothesis

  I am investigating what affects the resistance of Ni-Chrome wire. The main variables I could test are the thickness of the wire, the length of the wire and the temperature of the wire.

  I am going to investigate how the length of wire affects the resistance of Ni-Chrome wire.

What is Ni-Chrome wire?

  Ni-Chrome wire (NiCr60) is a Nickel and Chrome Alloy it consists of the following elements nickel: 57-58%, chromium: 16%, silicon: 1.5%, iron: Balance. Ni-Chrome wire is commonly used as a resistance heater for cutting foam (Styrofoam, polyurethane, etc.) fabrics, and a variety of other materials.

What is resistance?

  Resistance is the electrical term used to describe the property that various materials have to restrict or slow down the flow of electricity or current. Electrical resistance is low in most metals and high in most non-metallic materials. Electrical resistance is measured in ohms (Ω).

  I am going to use this formula calculated by George Ohm to calculate resistance.

 Voltage / Current = Resistance            V

     V / I = Ω                                      I      R

      Diagram to show the movement of electrons through a wire

  I predict that the longer the length of wire the more resistance will occur.

...read more.

Middle

Amp meter                 Volt meter             Ni-Chrome wire

  • Place a piece of 10cm of Ni-Chrome wire in the circuit
  • Increase or decrease resistance using variable resistor to keep the amps at 0.25
  • Measure the current and voltage
  • Repeat but increase the length of Ni-Chrome wire used in increments of 10cm until you reach 100cm
  • Increase or decrease resistance using variable resistor to keep the amps at 0.25 for each of the increments to keep the experiment fair.
  • Repeat the experiment 5 times, so you can rule out odd results easily.
  • Calculate resistance

Results

Experiment 1 (0.25 A)

Length of wire (cm)

Volts (V)

Resistance (Ω)

10

0.04

0.16

20

0.1

0.4

30

0.18

0.72

40

0.22

0.88

50

0.26

1.04

60

0.3

1.2

70

0.35

1.4

80

0.4

1.6

90

0.45

1.8

100

0.5

2

Experiment 2 (0.25 A)

Length of wire (cm)

Volts (V)

Resistance (Ω)

10

0.05

0.2

20

0.1

0.4

30

0.15

0.6

40

0.2

0.8

50

0.25

1

60

0.3

1.2

70

0.35

1.4

80

0.41

1.64

90

0.48

1.92

100

0.5

2

Experiment 3 (0.25 A)

Length of wire (cm)

Volts (V)

Resistance (Ω)

10

0.05

0.2

20

0.11

0.44

30

0.17

0.68

40

0.2

0.8

50

0.26

1.04

60

0.31

1.24

70

0.35

1.4

80

0.41

1.64

90

0.45

1.8

100

0.52

2.08

...read more.

Conclusion

Evaluation

  Overall all the evidence and experiments have concluded to me that my prediction is correct.

  In my results there were few odd results however when I put my information into a graph I saw a result that obliviously was out of place as it never followed the general pattern as well as the results for the other length of wire.

 I think this occurred because of one of the following reasons either of a miscalculation, error reading measurements or faulty equipment, to rule out these errors I could have used a data logger to gather my results to make them more accurate a reliable.

When caring out my experiment I think could have made other improvements to my experiment techniques such as measuring the Ni-Chrome wire. Instead of just having one long piece of Ni-Chrome wire and connecting the crocodile clips at the length needed.

  I could have had a piece of wire for each measurement. I could also have done more experiments to get rid of the anomalies.

  To further my investigation I could carry out other tests such as using thicker wire the see if it effects resistance, or change the temperature of the keeping the wire at various temperatures and then carry out the experiment to see whether it effects the resistance.

...read more.

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Here's what a star student thought of this essay

4 star(s)

Response to the question

A very well organised coursework that has divided its answer into different parts to create a basic understanding in the beginning before solving the main question. The answer definitely provides a very good procedure to solve this problem that does ...

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Response to the question

A very well organised coursework that has divided its answer into different parts to create a basic understanding in the beginning before solving the main question. The answer definitely provides a very good procedure to solve this problem that does not leave many unanswered questions for the reader, however it contains some errors especially in diagrams which have mostly risen by human careless mistakes that are mostly neglected by general readers.

Level of analysis

A good procedure that includes some errors such as lack of a voltmeter in the first diagram, and the wrong connection of the voltmeter in the preliminary setup (connected in series) however the main diagram is perfectly alright. It would have been great if the author could recap the resistance formula before using it in the experiments to calculate the resistance. most of the analysis is correct except the mention of extrapolating. Extrapolating is an accurate method to "predict" the value of resistance which is out of our experimental range of wire length, only for values close to the experimental range. predicting the resistance of a wire of length, 110cm would be alright, however predicting the resistance of a wire of length of 200cm would be inaccurate and unacceptable. experiment 3 was quoted as the least accurate experiment but the values found are within the instruments error range. Evaluation of results is good however faulty equipment could not be a reason for inaccurate results since the same equipment was used throughout the experiment.

#3

There are hardly ever grammatical or spelling errors and the author has used technical terms correctly. The quality of writing is fine and there are not many problems to be pointed out. In general it is a very good coursework that with a little bit of changes, it could be among the very high A* works and even close to a full mark.

Quality of writing


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