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. This is because the longer the wire the more atoms present consequently this increase the amount of times that the electrons collide with the atoms, therefore increasing the resistance. This was also show within my preliminary results as increased the amount of filament bulbs (in affect increasing the amount of wire) the resistance increased.
Resistance:
x = length of wire x = R = V/0.25
0.25 = Amps 2x = 2R = 2V/0.25
V = Volts 3x = 3R = 3V/0.25
R = resistance 4x = 4R = 4V/0.25
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Peer Reviews
Here's what a star student thought of this essay
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.
Response to 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.
Quality of writing
Spelling and grammar are of a high standard. However, one thing that I would mention is make sure that all data is clearly presented and grouped on only one page and try not to span it over more pages. Another thing that the writer should also look into doing page numbers.
Level of analysis
The scientific language of the writers report was correct and of a high standard. However once thing that I would have to mention in regards to this point is that for any experiment you do, you should always draw a graph to make sure you can have another way to verify the relationship that you are trying to show.
Response to question
This is a well written report, where the writer has gone into a lot of detail in order to validate their hypothesis. It was very good for the reader to explain the theory behind the experiment and trends that they were planning to spot. This also includes the preliminary experiment that the writer also carried out. The main investigation was carried out to a high standard and went into a lot of detail. The writer had made sure that all the preparation was clear to the reader before taking any form of results. The writer also observed that keeping the current constant would have meant that the experiment was fair. What the writer should have done though it try and keep all of the data per experiment on one page (so for example, experiment 5 goes onto two pages when this could have been avoided). It was disappointing that a graph was not drawn to show the resistance of the wire, but it was good that the writer explained that if they changed the current what the graph would have looked like. The evaluation was also good.
