Introduction: (Initial Observation)
Magnets can be made by placing a magnetic material such as iron or steel, in a strong magnetic field. Permanent, temporary and electromagnets can be made in this manner.
The atoms forming materials that can be easily magnetized such as iron, steel, nickel, and cobalt are arranged in small units, called domains. Each domain, although microscopic in size, contains millions of billions of atoms and each domain acts like a small magnet. If a magnetic material is placed in a strong magnetic field, the individual domains, which normally point in all directions, gradually swing around into the direction of the field. They also take over neighboring domains. When most of the domains are aligned in the field, the material becomes a magnet.
Before Magnetization
After Magnetization
When an object becomes a magnet, it will have two poles. Magnet poles are called north and south poles and are marked by N and S letters.
In magnets, like poles repel and unlike poles attract each other. In other words if we attempt to connect the North pole of one magnet to the north pole of another magnet, it needs a lot of force and if the magnet is strong enough, it will more likely jump out of our hands.
In this project we want to try to use the repelling properties of like poles to make levitating objects such as a levitating train.
Information Gathering:
For more information about magnets click here.
Click Here to see related information from University of California, Los Angeles.
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is experimenting the repelling properties of magnets and exploring ways that such properties can be used in industrial products.
I have also noticed the repelling force of two magnets when same poles face each other varies by the distance of magnets. The repelling force increases when two magnets get closer to each other. In this project I will also try to find out:
“How is the repelling force of two magnets is affected by their distance?”
Identify Variables:
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
The independent variable (also known as manipulated variable) is the distance between two magnets with similar poles faced to each other.
The dependent variable is the force in which two magnets are repelled from each other.
Controlled variables are temperature and external magnetic forces. We make sure that no external magnetic force and no temperature change is affecting the repelling force between two magnets.
Constants are the type and size of magnets, method, procedures and test instruments.
These variables are investigated in experiment 4, below.
Hypothesis:
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
My hypothesis for effect of distance on repelling force:
I think the repelling force multiplies as distance reduces. The multiplication factor is probably very high because when the magnets get very close, it will be very hard to keep them together.
This hypothesis will be tested in experiment number 4, below.
Experiment Design:
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment 1:
In this experiment we insert two small bar magnets in a clear plastic tube in a way that like poles face each other. First magnet went to the bottom of tube, but the second one float above the first one. The second magnet could easily go up and down like it is on a spring.
Experiment 2:
In this experiment we insert a wood dowel into a few ring magnets. Ring magnets are arranged in a way that like poles face each other. Although magnets can freely move up and down, they do not fall on each other and all magnets will levitate above the first one.
Experiment 3:
This experiment is an attempt to make a levitating train.
Use two long magnetic strips as rails; glue them to a long piece of wood (as a base or ground) in a way that the North side of the magnetic strip stays up. Also use a smaller piece of wood as a train and in the same way glue two magnetic strips at the bottom of the train. Now, if you place the train on the rail it should levitate because the North Pole of rail and train magnets are faced to each other. The train might slide to the left or right and that also can be controlled by side rails.
My Details:
I had a 3-foot piece of wood (about 5″ wide and 1″ thick) that seemed perfect as a base or ground for the rails. I also cut a 6″ piece from a 1″x2″ to be my train.
I used two ½” x 24″ high-force magnetic strip as rails and two ½” x 5″ as the train wheels.
I wanted to use a compass to identify which side of the strip is north and which side is south; but instead I used another magnet that was already marked N and S to do that. That side of the strip that pulls the S side of my magnet is north. I tested and marked all my magnet strips to make sure that the N side of rail will face the N side of the train magnet.
Gluing the magnet strips was another challenge. Finally I used what is known as contact cement. The way that contact cement is used is totally different from other glues. For contact cement you apply the glue to both surfaces and wait about 10 minutes and then you put the parts together and apply force. I recommend reading the instructions on a contact cement container for details.
Since the N side of magnets are supposed to be faced to each other, I applied contact cement to all S sides. I also marked the location of the rails and applied contact cement there too. (The distance between magnetic strips on the rail and on the train should be the same; so I had to do some measurements and calculations as well.)
After about 7 minutes, when the glue was almost dry, I placed magnet strips on the wood and applied some force to secure them. As instructed on the contact cement packaging, I then placed some heavy books and other objects on the magnet strips and left them for a few hours for a good contact.
Now I was ready to do my first test. I placed the train on the rail and as I guessed, it started to shift to left or right; so I really need some sidings or guard rails.
I had some wood moldings that seemed suitable as sidings. I glued them and tested; but the result was not good.
There was too much friction between the train and the sidings. So I took them out and installed some plastic angels. Plastic angles have a smooth and slippery surface and do not cause much friction. The result was great and the train had a smooth ride. There was one small problem though. The train had tendency to flip because it was too light.
I could possibly find a heavier wood for the train or use a metal piece as a train; but I decided to attach some weights to the front and back of the train and that helped. Finally, I did some quick decoration on the train.
Experiment 4: (Main Experiment)
How is the repelling force of two magnets is affected by their distance?
Procedure:
- Perform the experiment number 2 with only two ring magnets.
- Measure the distance between two magnets.
- Make a paper tube, glue a cardboard on the top of that, weight the paper tube and cardboard, place it on the upper magnet and measure and record the distance again.
- Add different weights on the top of the cardboard and for each weight record the distance between magnets in a results table that may look like this:
| Weight | Distance |
- Use the above results table to draw a graph.
Experiment 5:
Will the size of the battery change the power of the electromagnet?
Introduction: The power of electromagnet can be measured in many different ways. In this experiment we will use the repelling properties of magnets and arrange a test method in which one magnet floats above the electromagnet.
Procedure:
- Insert a bolt or screw in a wooden board in a way that about 2.5 centimeters (one inch) of that remains outside.
- Wrap a layer of paper or masking tape over the screw to form a smooth surface.
- Wrap 500 to 1000 turns of insulated copper wire (magnet wire) over the screw. Use thin wire so the coil will not get very bulky. Wire gauges of 27 or more are preferred. (as the wire gauge increases the thickness of the wire decrese)
- Remove the insulation from the ends of wire where you will connect the battery.
- Wrap another layer of tape over the wire coil to prevent unwinding.
- Place a block of wood the same height as the screw top about 10 centimeters (4 inches) away from the screw and secure it using nails or wood glue.
- Cut a strip of thin wood (such as Popsicle stick) from the middle and then use a flexible tape to join them again. This will make a hinge-like structure.
- On one end of the wooden hinge attach a magnet disk and secure it with tape. Connect the other end to the wooden block. At this time the magnet must be right over the screw and touching it.
- Connect the ends of the wire to the polls of a 1.5-volt battery. Does the magnet disk float? If it does not, reverse the connections to the battery.
- Measure and record the distance of the magnet disk to the electromagnetic screw.
- Repeat this experiment with 6 volt and 9 volt batteries as well. By connecting batteries in series you can create other voltages as well. The distance of the disk magnet from the electromagnet is an indication of the strength of electromagnet.
Materials and Equipment:
When I started this project, I thought I had plenty of wood at home and I could get the magnetic strips from a broken refrigerator door, but it did not work that way. The magnetic strips used on refrigerator doors are too narrow and do not have much force.
I had my woods ready and was still looking for a high-force magnetic strip. Even the one that I bought in our local hardware store was not strong enough. Finally I bought a magnet levitation kit (available at MiniScience.com) and that had high force magnetic strips that I could use. Magnet levitation kit also included small pieces of wood to be glued to each other to make the base, but I preferred to use my own wood. Inside the magnet levitation kit there was at least 20 other pieces of magnets that I had no use for them. Among them was some latch magnet that used a pair of those as a weight for my train. There also was a nice super magnet that I saved for my collection.
I am planning to use the ring magnets of the kit to build a magnetic spring later.
This is the list of material that I used:
-
- pine wood 36″ x 5″ x 1″ as a base
- pine wood 6″ x 2″ x 1″ as a train (I prefer a heavier wood)
- two ½” x 24″ high force magnetic strips (From kit)
- two ½” x 6″ high force magnetic strips (From Kit)
- Contact glue (From hardware store)
- small brush, available at any art store or hardware store
- 24″ angel plastics (comes in the kit but in small pieces. I got a long one from a local hardware store)
Results of Experiment (Observation):
Although magnet levitation is possible, it needs a lot of controls and calculations.
High speed trains made based on magnet levitation technology must have a very complicated and delicate instrumentation to control the amount and direction of magnetic forces. It seems to me that I could use magnet strips on the sides of the train and on the guard rails as well to ensure no physical contact between the train and outside, but I have not tried that.
Calculations:
The wood that I used as a train is known as 1″ x 2″, but it really was about 1.5″ x 3/4″, so I had to do some measurements and calculations to find the proper distance between rails such that the magnets on the train be aligned to the sides of the train.
Summary of Results:
Although the train finally had a smooth ride, it continuously had contact with sidings or guard rails.
Conclusion:
We already have millions of uses for magnets and magnetic forces. Electricity, Telephone, Television, computers and many other appliances could not exist without magnets. As technology grows we will find more uses and more applications for magnets and magnetic forces. Possibly many of future inventions will be based on magnet levitation.
Related Questions & Answers:
Does magnetic force of a magnet have a relation with the size of that magnet?
The answer is No. Magnetic force depends on the formula or ingredients of a magnet. Neodymium Magnets are the strongest solid state magnets made today. Despite the small size, they are many times more powerful than many large magnets. Maybe that’s why they are also called super magnets.
Possible Errors:
In designing my magnetic train, I constantly had a regular train in my mind and that could be a problem. Magnets do not function like wheels and maybe a magnetic train must not look like a railroad train. Possibly there are better designs for magnetic trains that needs to be discovered.
Question: what would be my purpose and hypothesis for the magnetic levitating train ?
Answer: Construction of a train is not an experimental project. The purpose is exploring the problems and possibilities. The train project will demonstrate one of the applications of magnet levitation. I suggest doing the experiment 4 as your main project so you will have variables and testable hypothesis.
If you really have to use the train experiment as your main project, you can make up a purpose and hypothesis like this:
The purpose of this project is to find the effect of load or total weight on the friction force in a levitating train. In regular cars, trains and boats the friction will increase with load. I am wondering if the same will happen with levitating trains.
Independent variable is the weight, dependent variable is the force to pull or push.
A sample hypothesis is: More load on the train will increase the friction forces needed to pull the train.
In your experiment you must use a sensitive spring scale to pull the train. Sensitive spring scales are low range spring scales such as 0-10 gram scales. A low range Pen Scale available at MiniScience.com is one type of spring scales you may use. Record the force needed to pull the train. Then increase the load by adding some heavy objects (50 grams at a time) and repeat the test. You will need to test at least 3 different total weights in order to have a conclusive result.
Make a data table like this to enter your results:
| Total Mass (Empty weight + added load) | Minimum force needed to pull and move the train |
To measure the force needed to pull the train, you can also use a thread that is hooked to the train from one side and is hanged down a pulley from the other side. By hanging weights to this tread you can measure the force needed to move the train.
Another project with Magnet Levitation Train
Purpose: Find out how far does the train travel if it is ejected by the force of repelling magnets. Does the total load or weight of the train affect the travel distance?
Variables: The independent variable is the weight of the train. The dependent variable is the distance it travels. Constant is the train. (Control variables are not defined because you will not try your experiment in different days and different environmental conditions).
Procedure: Use tape, glue or screw to attach one latch magnet on each end of the train car. (Latch magnets are the rectangle magnets with a hole in the center).
Mount a wood block on each end of the track to stop the train car on impact. On the wooden blocks mount latch magnets so that they will repel the train. This will reduce the impact force and can be used to eject or launch the train.
Place the train in the track and hold it against the latch magnet on one end. Then suddenly release the train so that it can move by the force of the magnet. Measure the distance it travels. Repeat this 3 to 5 times and record the average. Also weigh and record the weight of the train car.
Add some weight to the train and repeat the experiment 3 to 5 times with each new weight.
Finally record your observations in a table like this:
| Train Weight | Average travel distance after launch |
Make a graph
You can finally use your results in the above table to draw a bar graph. Make one vertical bar for each train weight. The height of each bar will be the relative distance the train travelled.
