The aim of my experiment is to see what factors affect electromagnetism the most so as to give the best electromagnet in an experiment.
Nicholas Marshall 10A Monday 1st July 2002
Physics Coursework- Electromagnetism
Aim-
The aim of my experiment is to see what factors affect electromagnetism the most so as to give the best electromagnet in an experiment. The factors I will use are: the number of coil wraps around the iron nail and the amount of current in the circuit. It is these factors that I will use to see which one gives the best electromagnet.
Scientific Knowledge-
How to get an electromagnet-
When an electric current flows through a coil of wire it sets up a magnetic influence or 'field' around the wire. The more turns of wire there are in the coil and the bigger the current, the stronger this magnetic field will be. An easy way to wind the wire is around an object and a winding like this is called a solenoid; if now an iron core is put through the hole in the coil it will become an electromagnet when a current is sent through the wire around it. The reason for using iron is that it concentrates and strengthens the magnetic field.
An Electromagnet in Electron Terms-
This part is quite simple. A current is made up of electrons, so when you say a current flows you could also say when electrons flow. So if a current creates a magnetic field then the electrons also create a magnetic field. So the flow of electrons gives a magnetic field, which in turn creates the electromagnet. So the electromagnet can be traced directly back to the electrons within a wire.
Magnetic Field-
If one considers the circular magnetic field round each short length of wire in the flat circular coil, it can be seen that the field adds up through the centre of the coil. This leads to a strong field through the coil but a weak one outside it (see diagrams).
A solenoid may be considered as a series of flat circular coils, each a little spaced apart from one another on a common axis. Each turn of insulated wire gives a magnetic field similar to that of a flat circular coil. The fields between neighbouring turns oppose one another and cancel, but the fields along the common axis reinforce, producing the pattern shown below.
I can say from this that because the magnetic field occurs most strongly on the inside of the circular wire that if an object of a specific material is placed through the circles then a magnetic field will be induced into it, which is why it becomes an electromagnet.
From these quotes I also know now that the magnetic field only occurs near and inside the coil wraps. Therefore magnetism will also be strongest in those same places.
Plan-
From my scientific knowledge I can make a reliable plan.
Equipment-
First of all the equipment, I need:
An electric current, so a power pack,
The coil to create the solenoid,
An iron nail to create the electromagnet,
And some wires and crocodile clips to connect the circuit together.
Some equipment to measure and control the experiment will also be needed, so an;
an ammeter to measure and...
either the power pack can control what current it lets through or a variable resistor (which also controls what current is let through but is an extra item within the circuit). Of the two the variable resistor is more accurate.
And lastly some equipment to measure the power of the electromagnet (this will be found out after further analysis).
Method-
Using the equipment above I can create a fair and reliable circuit. To make it I will connect the left side of the power pack to an ammeter with a wire. From the other side of the ammeter I will use another wire to connect the ammeter to the solenoid. This solenoid will have an iron nail through it so as to create the electromagnet. On the opposite end of the solenoid a wire will connect it to the right side of the power pack thus completing the circuit. If I will include a variable resistor it will go in between the power pack and the solenoid/ electromagnet using an extra wire. After the circuit is complete I will switch the power pack on to get a current flowing through the solenoid. To create the electromagnet I will basically wrap a piece of wire around an iron nail. The diagram below explains it in a simpler form.
Diagram-
Ammeter
Power pack
:+ x amps crocodile clips Coil wrapped
around the nail
x amount of times.
Variable resistor
The dotted line above in the diagram shows where I will include the variable resistor if I use it.
At the moment all I've talked about so far in my method is how I will make the experiment. I will now say how I will do the experiment. First of all before I start I will record all the experiments factors, which includes:
. Recoding the current in amps and...
2. recording the number of coil wraps.
When doing the test I will have to find a suitable method to measure how good the electromagnet will be when varying the factors. Since it is the magnetism that I am experimenting on and that a main point of magnetism is its ability to attract other objects I think that the best way to test it out is by putting certain amount of objects onto the electromagnet. The bigger number of the objects that the electromagnet can hold on to the stronger and more efficient it is, which is the whole aim of my experiment. The objects will have to be big enough to handle (as I don't have tweezers) but small enough to make accurate measurements on. After some thought I think that paperclips are the best objects to use as they are attracted to electromagnets and can be measured in mass and number, they are also easy to hold and small enough to get accurate enough recordings on. Therefore the efficiency of the electromagnet will be measured in grams (the mass of all the paperclips the electromagnet can handle).
To get recordings of how the number of coils affects an electromagnet and how the current affects an electromagnet I will have to do two separate tests comparing the final results afterwards to see which is the most efficient factor to make the electromagnet stronger. To get the results of these two factors I will have to vary them within separate tests. To increase the accuracy of my results I will also repeat these tests.
Experiment that will be used to test how much a varying current affects an electromagnet-
In the varying current experiment once the circuit is set up and the initial amps and coil wraps are recorded I will place paperclips onto the electromagnet and see how many will stay onto it by magnetism. These numbers of paperclips will then be recorded. The current will then be increased using the variable resistor or the power pack and the amps recorded using the ammeter but I will keep the coil wraps the same amount. Paperclips will again be placed onto the electromagnet again and then the number that stays in place will be recorded again. This will be repeated up to a suitable amount of times (an exact number of test repeats will be found in the preliminary test).
Experiment that will be used to test how much you can affects an electromagnet by varying the amount of coil wraps around the iron nail -
When doing the varying coil wraps experiment I will do exactly the same as above but instead the number of coil wraps will be increased and the current will remain constant.
It is in the varying current experiment that the variable resistor may be used (this also will be determined within the preliminary test).
Fair Test-
When doing the experiment I must keep the factors that remain constant the same at all times. If they change then the electromagnet's performance may be hindered or increased both of which lowers the reliability of the results. This is called keeping it a 'fair test'. To keep the experiment as fair as possible I will have to do certain things. The most obvious thing to keep constant is the other variable that I am not changing, so when in the varying current test I must keep the coil wraps the same amount, the same ...
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Fair Test-
When doing the experiment I must keep the factors that remain constant the same at all times. If they change then the electromagnet's performance may be hindered or increased both of which lowers the reliability of the results. This is called keeping it a 'fair test'. To keep the experiment as fair as possible I will have to do certain things. The most obvious thing to keep constant is the other variable that I am not changing, so when in the varying current test I must keep the coil wraps the same amount, the same with the varying coil wraps experiment except that I have to keep the current constant. The less obvious factors, but just as important, are that I will have keep constant throughout both tests the thickness of the wire in the solenoid, the heat around the electromagnet (I know that the heat can't be absolutely controlled but I can make sure that it differs as little as possible) and that I am to use the same nail throughout all tests (results may differ from nail to nail because of varying material etc.). The paperclips should also remain of a constant material because a different material may affect how much it is attracted to the electromagnet, distorting the results.
The only factor left in electromagnetism are the fields that surround a solenoid. I have already explained how the magnetic field concentrates in the middle through a solenoid and as a result so will the magnetism. From this I can say that the coil wraps will have to be equally distanced apart so that there will be no concentration of magnetism in the iron nail (if any two coil wraps are nearer each other than usual then their two fields will combine to make a stronger magnetism in between them whereas any coil wraps further apart than usual the field will be weaker than usual). The whole point of this is so that I don't accidentally place all the paperclips in a weak area missing the stronger area and so getting a mass of paperclips lower than what I should get. To counter this problem (as it's very hard to get equally distanced coil wraps) I could space the paperclips evenly among the iron nail so that no weaker areas or stronger areas would be missed.
The coil wraps can't be side by side because then I wouldn't be able to place the paperclips in between them, which is where the magnetic field occurs most strongly. If I place the paperclips on either end of the nail where there are no coil wraps then I would expect to find little magnetism.
So when I'm doing the experiment I know now to place the paperclips either in between the coil wraps on the nail or as near as possible to them and I also know to space the coils equally apart when attracting or placing the paperclips.
Safe Procedure-
To make this a safe procedure I will make sure that there is no current going through the circuit when connecting the wires, this will make sure that I don't get an electric shock. I will also make sure that I don't put the current up to an extreme value so that I don't break any equipment and I won't touch any metal wire that is showing at either end of the coil to prevent again an electric shock. Lastly I will make sure that I don't fool around with the nail as it may get too hot to touch with a current going through it and plus it also may ruin the experiment or distort the results.
Prediction-
The prediction that I make here will be mainly concluded from my scientific knowledge. I know that to create an electromagnet I need a current flowing through a wire wrapped around a specific object (an iron nail to be precise) and I know that the current and the wire will affect the magnetism in some way if it is varied. But if I look at it in terms of electrons on how an electromagnet works I might get some idea of what will happen. The flow of electrons creates a magnetic field so I can assume that the more electrons there are the bigger the magnetic field will be and the bigger the magnetic field the stronger the electromagnet. The two main ways of creating more electrons to make the electromagnet stronger is either by creating more electrons at the source, this is to say to increase the current or by having more wire around the nail because the more wire there is the more electrons that can be held near the nail which should, in turn, create a stronger electromagnet.
Normal current After increasing After increasing the
the current amount of wire
I I I
= Electrons (in the direction of the current)
The diagrams above show how I predict the electrons will increase by either the amount of wire present or increasing the current. These two predictions completely relate to variables that I will use so now I can predict that as the current increases more paperclips should be picked up by the electromagnet and as the number of coils increase more paperclips should also be picked by the electromagnet.
I also predict that if the results are taken as accurately as possible there should be a straight-line ratio between coils and paperclips, and also between amps and paperclips.
When drawing the graphs
of my results I think that
Paper- Paper- their line of best fit will
clips clips look something like this.
Coil wraps Amps
The reason I predict this is because I think that there is a straight line ratio or 'direct proportionality' between the two items. This direct proportionality term means that if it exists within a graph then the two values being used have relation to one another (i.e. using a current value then the mass of paperclips value can be predicted by using a formula that is always used when getting values from the same graph).
I can't find any reason why either the number of coils or the amps should have a line that goes in a curved fashion. As the number of amps increase the magnetism should also increase and it's the same for the coils.
Although I cannot predict which variable will create the most efficient electromagnet, as I do not know how the electron output would vary from each variable, I can though predict that because there is direct proportionality that 2 x the amount of amps or coil wraps should give me 2 x the amount of paperclips. The better variable is something that I will have to find out purely from my experiment.
Plan conclusion
I believe that my plan is a suitable approach to solve my problem because it covers all the areas of my aim and also because all the points that I have made is backed up with scientific knowledge and so proven. The ultimate proof though will be seen through the success of my experiment.
When doing the actual experiment I will aim for accurate and reliable results and evidence. This will be done by following my method as close as possible, which, as I have said, is proven with scientific knowledge, and so should be reliable.
The last obvious thing that I will aim to do is justify my predictions. If I can do this then I will know that my method is reliable because my predictions are based on the same scientific knowledge that was used for it.
Preliminary test-
This test will be used to find out how many recordings to take, whether to use the variable resistor or not and to find out any mistakes that would happen if I were to start the experiment straight away. I will follow the method exactly as I have said and plot down some preliminary results.
Varying coil wraps experiment-
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
0
0.41
0
0
2
0.41
0
0
4
0.41
0
0
6
0.41
0
0
I now know that you get no results from 0-6 coils and so must start at least from 5 coil wraps and have bigger intervals in between so that more of a pattern can emerge. So during my actual experiment I will start form 5 coil wraps giving me a start of 0 paperclips and have intervals of 5 (going up in 5's, 5, 10, 15 etc.) up to 35 which should give me sufficient results. I see no problem with the current and so that can remain the same.
During my experiment I also noticed that the paperclips didn't just stick onto the nail, they had to be placed there. All this means is that instead of just passing the nail over a mound of paperclips I have to put on the paperclips to find the actual maximum mass the nail's magnetism can carry. I also observed that the current or amps kept on changing, to get over this obstacle in the experiment where the amps are supposed to remain constant I took a reading of the amps after every test and then at the end of the experiment I made an average of the amps and put it down in each test. Otherwise though the method went just as planned.
Varying current experiment-
During this preliminary experiment I will find out all that I found out in the other preliminary experiment except that I will also test out the variable resistor.
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
20
0
0
0
20
2.00
22
4.44
20
3.60
42
8.29
I wanted to go up in intervals of 2 amps but as you can see the maximum amp that my equipment will let me have is 3.60, any higher and the power pack cuts out. So during my actual experiment I will definitely have smaller intervals, intervals of 1 should get me enough results to see any patterns. I won't start at 0 next time because I already know that it will give 0 paperclips as there is no current to give any electromagnet at all and so I will therefore start just above 0 at 0.10 which should give me a useful result. I found out that the variable resistor is much more accurate than using the power pack to change the current so as a result I will use the variable resistor in my actual experiment to make my results more reliable. There were no problems with my choice of number of coil wraps so that will remain unchanged.
During both experiments I think that to get accurate results I will need to create two tables of results each for the different experiments and create an 'average' table out of the two tables (plus the corresponding results together and divide by two to get a single result). The graphs afterwards will therefore be based on the more accurate 'average' tables.
Experiment-
While I am actually doing the experiment I will apply all that I've said in my method and all that I found out in my preliminary experiment and so will hopefully come up with some very accurate results.
Results-
The experiment where the coil wraps vary-
In this experiment I used the number of coils as a variable, everything else should stay constant.
First set of results
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
5
0.41
0
0
0
0.41
0
0
5
0.41
2
0.4
20
0.41
4
0.81
25
0.41
9
.84
30
0.41
4
2.81
35
0.41
6
3.23
Second set of results
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
5
0.41
0
0
0
0.41
0
0
5
0.41
2
0.4
20
0.41
6
.22
25
0.41
9
.63
30
0.41
2
2.46
35
0.41
6
3.21
Average set of results
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
5
0.41
0
0
0
0.41
0
0
5
0.41
2
0.4
20
0.41
5
.01
25
0.41
9
.83
30
0.41
3
2.66
35
0.41
6
3.23
The experiment where the current varies-
This was the experiment where the number of amps changed and everything else kept constant. It also included the variable resistor.
First set of results
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
20
0.10
0.46
20
.00
4
2.19
20
2.00
24
4.83
20
3.00
33
6.57
20
3.60
43
8.63
Second set of results
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
20
0.10
3
0.46
20
.00
2
2.19
20
2.00
24
4.83
20
3.00
33
6.57
20
3.60
45
8.99
Average set of results
Number of coil wraps
Current (Amps)
Number of paperclips
Mass (grams) of paperclips
20
0.10
2
0.46
20
.00
3
2.59
20
2.00
24
4.83
20
3.00
33
6.57
20
3.60
44
8.81
Results - Graphs-
These graphs, as I have said before, will be based on the two third tables from the experiments because they are more accurate as they are average results of the two tables before it.
st experiment using the number of coil wraps as a variable-
In this graph there is a definite increasing trend to the points and although it looks like it curves upward I don't think it's supposed to it's just the two nought results that create the illusion; therefore the line of best fit will be straight. Because the line of best fit will be straight I already know without any calculations that there is a direct proportionality between the number of coil wraps and the mass of paperclips attracted to the electromagnet.
This bar chart compares the number of coil wraps to the mass of paperclips (using the y axis as both the number of coil wraps values and the mass in grams values). It basically tells me that the number of coils has to increase dramatically to increase the mass of the paperclips. I will later compare this chart to another similar chart, but includes the current as a variable instead, not the number of coil wraps, and see which one needs to increase more to get more paperclips attracted to the electromagnet. The variable that needs to increase lees I can conclude is the best variable out of the two to use that makes the electromagnet most efficient.
2nd experiment using the amps as a variable-
This also has an increase in its points. The points are in a fairly straight line so the line of best fit will also be straight which means that there is a direct proportionality between the current and the mass of paperclips attracted to the electromagnet.
This bar chart shows me that the mass of paperclips has a higher increasing trend than the current.
Graphs Conclusion-
From the two bar charts I can basically say that the number of amps has a closer ratio to the mass of paperclips than the coil wraps. From the scatter graphs I can see little difference when only looking at it so I can only say that they both have a positive direction but I wouldn't comment on how steep the line is because the two values of the variables within the two graphs are not in ratio to each other (and can't be because they are not the same values).
Experiment Conclusion-
First of all lets remind ourselves of the aim of my experiment; to find out which factor (current or number of coil wraps) affects electromagnetism the most to give the best electromagnet. In my conclusion I will answer that question along with any other questions that were put up within my prediction, most of which can be answered from the graphs and charts.
First of all I will answer the most important question, the aim. By comparing the two bar charts against each other I can see that increasing the current is the most efficient way to make the electromagnet better. This is because the bar charts compare the variable in question against the mass of paperclips the electromagnet can pick up in any one test. When looking at the bars the less space between the value of the variable and the mass of the paperclips the better, because less energy is being expended to get more mass of paperclips, and the variable with the least space between itself and the mass of the paperclips was the current. This shows that the current can expend less energy and get more paperclips than the coil wraps can.
Now that my aim has been answered I can now prove any predictions that I made earlier. The first prediction I made is that as the current or the number of coil wraps increase so does the mass of the paperclips. This is obviously proven by my line of best fit graphs as they both have a clear increasing trend to their points. I believed this to be so before because as the current increase so the does the amount electrons within the current's flow and I also explained before that an electron has a magnetic field around it and so as a result as the current increases so does the magnetic field. This magnetic field is then concentrated within an iron core (the iron nail) to create the electromagnet and the electromagnet gets stronger with the increasing electrons. So as the current increases so does the amount of electrons and so does the power of the magnetic field and then so does the power of the electromagnet. It was for this reason why the electromagnet increased in the amount of paperclips it picked up as the current increased. The reason why the number of coils increased the mass of paperclips the electromagnet picked up is because the wire holds the electrons that creates the magnetic field, a field that can be concentrated into an iron core to create an electromagnet. If the amount of wire increases then so does the amount of electrons, which leads to a stronger electromagnet. It's for this reason that the mass of paperclips being picked up by the electromagnet increased as the number of coil wraps increased in number.
The second prediction I made was that the variables would increase in direct proportionality to the mass of paperclips. This is true because both of the lines of best fit have variable values that correspond somehow with the mass of paperclip values. This can seen by the fact that the lines of best fit are both straight. This doesn't mean though that as the variable doubles so does the mass of paperclips (in fact neither of the graph's lines do that). To get the corresponding paperclip's mass value from a variable value on the graph then the chosen variable value will have to be multiplied by another calculated value called a 'constant'. So a formula appears:
Mass of paperclips = the 'constant' value x the variable value.
Or
Y = K x X
The constant value will differ from graph to graph but within the same graph the constant will always remain the same no matter how much the mass of paperclips or variable values changes. As a result of there being no 1:1 proportion in either graph I can say that a part of my prediction is wrong; as the current or number of coil wraps double the paperclip mass does not also double, although the second experiment is very close and so this statement is arguable.
To prove this proportionality I will do calculations using the above formula in the two graphs.
Experiment where the number of coil wraps is the variable-
In this graph is a complication because the line of best fit doesn't start from 0 on the number of coils axis. So where the line of best fit touches this axis I will have to minus this value from the number of coils value in each formula. To explain this I will say that the constant will have to be above 0 so that others values within the formula will also be above 0 to give a correct answer. But when a value of the number of coils that is above 0 but gives 0 grams of paperclips (which is possible if you look at the graph) and is multiplied by the constant value it is going to equal a number above 0. So therefore the highest coil value that gives 0 grams of paperclips will have to equal 0 within the formula. This means that it will have to minus its own number in order to get itself to be 0 so that when it is multiplied by the constant the answer will be 0. Any value above this specific coil number will still have to minus this value but since it is bigger than the minus number then it will give a value of grams that is above 0 as its answer to the formula, and should also be correct. This specific number on the above graph is 11.5. For every formula for this graph the coil number will always minus 11.5. When doing the Y = K x X formula on a graph the first thing that you do is figure out the constant (K). So if I get the corresponding mass of paperclips (Y) to the number of coils (X) by drawing a line that uses the line of best fit then I can figure out K. This line is marked on the graph as 1.
.
Y= 1.15
K= ?
X= 20
.15 = K x (20 - 11.5)
K = 1.15 / (20 - 11.5) = 0.135
This number is my constant and if it works it proves that my graph proportional values which proves part of my prediction. So I will now use this formula to predict another gram value and then see if it right by drawing another line on the graph that uses the line of best fit. This line is marked as 2 on the graph.
2.
Y= ?
K= 0.135
X= 30
Y = 0.135 x (30 - 11.5) = 2.4975
The line on the graph tells me that the corresponding gram value to 30 coil wraps is 2.5. They are nearly exactly the same and so proves the part of prediction that said that the number of coils is proportional to the mass of paperclips.
Experiment where the amps are the variable-
Since this graph has a line of best fit that starts from 0 there a no complexities. I will do as I did before- the line to find out my constant is marked as 1 on the above graph and the line to prove my prediction is marked as 2 on the above graph.
.
Y = 2.4
K = ?
X = 1
K = 2.4 / 1 = 2.4
This formula will prove my prediction.
2.
Y = ?
K = 2.4
X = 3
Y = 2.4 x 3 = 7.2
From the line the corresponding value to 3 amps is 7.2 grams. The formula and the graph value are exactly the same and so proves that there is proportionality within the two values and so proves another part of my prediction that there would be proportionality between amps and the mass of paperclips.
The reason why a straight line of best fit exists in both graphs is because there is no reason why they should curve. As the number of coils or the current increases so does the power of the electromagnet. Firstly because the wire has a current running through it, a current which hold electrons that creates a magnetic field, which can be concentrated into an iron core when wrapped around it in like a coil. As more coils are made around the object the length of the electromagnet increases but so does the power because each coil holds a certain amount of electrons (electrons are the things that create the magnetic field) that are used to strengthen the electromagnet. As the current increases although the amount of electrons also increase and so does the magnetic field, which in turn also increases the power of the electromagnet. So as the current increases so does the mass of paperclips being picked up by the electromagnet. There is no reason within these explanations why the power of the wire should increase or decrease between intervals to give an upward or downward curve to the line on a graph- each coil has the same amount of power as the last and there is no more power after each amp within a current, so the line of best fit stays straight, not curved, which gives a direct proportion to the graph.
Evaluation-
Analysis of the method and results-
I am pleased with my method and results as they turned out to be quite informative. I believed that I used a good method because I didn't get any anomalous results and also because the results when plotted on a graph all lie close to a straight line.
Observations-
During both experiments I found that by repeating my tests I got much clearer results because, as you can see, the results did vary slightly from the two times I got them which made them inaccurate, whereas an average gave one result by combining the two that I have got. I also noticed some details that affected the experiment overall.
The first one I noticed during the coil wraps experiment, it happened when the power pack was switched off on a particularly high number of coils and the paperclips still stuck to the nail even without a current. I could only conclude that a charge is left over from the previous test in the nails (or the nail, but that is unlikely as iron loses its charge quite quickly so it's most probably the paperclips retaining the charge). This must mean that the next test is affected in some way, which might affect the next set of results. The other observation I made was the size of the paperclips and how much room they took up on the nail. Technically the smaller the paperclip the more accurate the results because you can get a more detailed mass result but what I found is that there wasn't enough room on the nail to fit all the paperclips so even if I wanted to I couldn't go above 4 amps in the test as the paperclips wouldn't fit. This means that if I were to do the experiment again in more detail I would need a bigger nail (from this I could also see how the size of the nail affects the magnetism by comparing to my old results). During the varying coil wraps experiment I noticed that the first two results were both nought, which tells me that my current was too low; this lowers my accuracy as the two results were invalid and cannot contribute to my experiment whereas two more results would have improved reliability.
Changes that would be made if I were to repeat the experiment-
If I were to change my experiment I would try using something other than paperclips to see whether it would give me more accurate and reliable results, maybe iron filings because they would be more accurate in weight as they are smaller. I would also use a better power pack that can exceed 4 amps so that I could take more readings and get bigger graphs to see if my straight line continues on. I would also, as I have said, increase the size of the iron nail to be able to fit more paperclips on it so that I could fit both more coil wraps and more paperclips which would again increase my results capacity.
To increase the reliability of my results I would use fresh paperclips after each test because I believe that a paperclip that has just been used in a test still has a magnetic charge left over and so if used again would distort the results. Lastly in the coil wraps experiment I would change the values so that I would start on 10 coil wraps instead of 5 so as to get rid of a 0 (I still want to keep a 0 so that I can have a starting point) and go up to a higher number of around 100 coil wraps so that I can get a more detailed line of best fit. I would also increase the number of results to take down in the current experiment if the power pack would exceed 4 amps.
The reliability of my results-
Since I had followed my method exactly, which was proved to be reliable in my scientific knowledge, I believe that my experiment went fine, of which is proven because I gained reliable results. This is because there are no anomalous results and that they managed to prove most of my prediction, which was created using scientific knowledge. The fact that everything that was proved was based on scientific knowledge adds to the reliability of my evidence as it follows safe and exact information.
Do my results support a firm conclusion-
I think that for my aim there were enough results, as I only needed a few results to confirm any pattern within the variables to see which one made the better electromagnet. As for the direct proportionality I do believe that my conclusion is right but if I were to make sure and know that I was right I think a lot more results would have to be taken to create extensive graphs and see whether the line does stay constantly straight.
Further work to prove my conclusion-
To prove my direct proportionality even further I could just predict a result by using extrapolation on my current line of best fit or the direct proportion formula: mass of paperclips = the 'constant' value x the variable value, in a graph and then repeat the test using the corresponding values to the prediction and see whether or not I am right. If I am near enough right then I can make my conclusion firm because I would know that the line carries on in a straight way at least to that result.
The obvious thing to do to prove the conclusion of my aim even further is to take more variables into my experiment and see whether or not the current stays the best way to increase the magnetism in an electromagnet. The variables might include the thickness of the wire and the material of the nail. The thickness of the wire would be a good variable because it could also affects the amount of electrons in the wire as the wire could hold more in it after each coil wrap. My prediction would be; because the wire is thicker more electrons are let through which would increase the magnetism so as the thickness of the wire increases so does the magnetism. To include it in an experiment all other variable would have to stay constant (the number of coils, current etc.) and then different sets of wire with varying thickness would be wrapped around the wire and the results recorded.
The nail is also a good variable because the nail is a main part of the electromagnet and its material affects the magnetic field that is induced into it. My prediction for this variable is; the different types of material will affect the amount of the magnetic field induced into it. I predict that the materials that conduct more (heat and electricity) will create a better electromagnet as it's conducting more of the magnetic field through it. If an experiment was to be done on this then all other variables would have to stay constant and only the nail would be replaced. On every test the nail would be replaced with a new material and its results recorded.
Overall though I think that this was a very successful experiment and that I have managed to gain and analyse some useful results that told, explained and answered me a lot. I have also set myself some more questions for me to answer in any other extra experiments that I may do in the future.