Resistance of a Wire
Planning
I am going to measure the resistance in  (ohms) of different points along some
Nichrome wire.
The evidence will be valid because I will change the voltage (V), any other variables
will not be changed by me. Also I will do the experiment twice.
Suitable equipment that will be used will be a cell, a variable resistor (Nichrome
Wire), a voltmeter and an ammeter.
A
V
I will be setting up the circuit as shown above, and what I will vary will be the length
of Nichrome wire in the circuit. The things to keep the same will be the voltage and
the amount of wire used in the rest of the circuit. My prediction is that the more of
the Nichrome wire put into the circuit, the higher the resistance will be.
The evidence I will collect will be the voltage, current and resistance of the circuit. I
will use 10 cm intervals for the difference in amount of Nichrome wire included in the
circuit. The total range will be 100 cm. The evidence will be reliable because I will
do the experiment twice to check for reproducible results and to counter any mistakes
made during the first attempt. I will only be reading the voltage and the current, the
Voltage
resistance I will calculate by using Resistance = Current (R = VC ).
My prediction is that the more Nichrome wire included, the higher the resistance will
be because the more wire, the higher the chance of the electrons colliding with the
other particles in the wire.
Previously in this course I have calculated the resistance of wire after changing the
voltage, this is similar, but this time I will be varying the length of wire.
Analysing and Considering Evidence
I have found out that different lengths of wire have different resistances.
The longer the wire, the higher the resistance. The resistance was higher the more
wire there was because there are more particles to move through, therefore there is
more chance of the electrons colliding with other particles in the wire.
^ These 4 electrons would hit a certain
number of particles of wire by the time
they reach the end of the section of
wire.
< The same 4 electrons would on
average hit only half the electrons, if
they travel half the distance.
This conclusion supports my prediction because as I predicted, the higher the amount
of wire in the circuit, the higher the resistance.
Evaluation
I think my results were good because the fitted with the pattern I expected to get.
I think that my results are accurate, I can say this because all the points on the graph,
for both attempts of the experiment, are close to the line of best fit. There were no
anomalies in the results.
The procedure was suitable, however to change it next time I would find a way to get
the Nichrome wire on the metre stick tighter, this would make sure that each
measurement was more accurate.
My evidence for my conclusion is very reliable as it supports my prediction, and also
it has a clear explanation that agrees with my results. The reason for there being no
anomalies is because it was measured accurately, and I was made sure that the voltage
was the only thing changed.
Also to improve the quality of my results, I could have ensured that the Nichrome
wire stayed the same temperature throughout the experiment. This is because without
temperature control the higher the voltage, the hotter the wire will be. And the hotter
the wire is the particles will be moving around more, therefore increasing the chance
of a collision with the electrons.