When a solenoid is connected to a voltage source, there is a current along the wire
There will be a constant, uniform magnetic field through the centre of the wire coil
First Attempt
First Attempt
Connected both ends of the wire to the battery and placed the magnets inside the coil
There was no interaction with the field to move the magnets
In a magnetic field, a north magnetic pole will be pushed in one direction and a south pole in the other
North and south poles are always found together, so if you just put a magnet in a magnetic field it won't move
The wire wasn't coiled smoothly or tightly
Second Attempt
Recoiled the copper wire to be tighter and smoother
Placed the magnets with poles facing opposite directions to create a bar magnet with north and south poles
As the electrical current flows through the wire, a magnetic field would be created in the section of coils in contact with the train
Train interacts with the north and south poles of the magnetic field to push the magnet in front and pull the magnet behind
Our Train!
Video
The
Physics
Why does it work?
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Ampere's Right-hand Rule
Electricity flowing through a long straight wire creates a circulating magnetic field around it
A field of force that will interact with any permanent magnet nearby
Permanent magnet will line its North pole with field lines, and will be drawn into a region with a stronger field
The direction of the field lines can be determined by Ampere's right-hand rule
Ampere's Right-hand Rule
Point the right hand thumb in direction of current along wire
Curl fingers inward
Direction of curled fingers gives the direction of the magnetic field
Magnetic field radiates outward in a circle
Its strength will decrease as the distance from the current carrying wire increases
If you follow along the curve of the solenoid with your thumb, the direction of the magnetic field will always be through the centre
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Magnetic Poles
A magnet will always have a north and south pole
A magnetic field can interact with magnets to cause a force upon the magnet in the field
How does this make a train?
A local circuit is made along the battery from the positive terminal, into the magnets, through the wire of the solenoid, and back into the magnets at the negative battery terminal
The magnets placed on either battery end cause the magnet poles to be pushed in and out of the circuit
This force causes the train to move
Pole Orientation
The same pole must be facing each other so the forces are in the same direction or they would cancel out and the train wouldn't move
If the magnetic field is non-uniform, there'll be a slightly bigger push on the north pole than the south
The field is strongest in the middle
Poles facing each other in the middle will feel a stronger push than those on the outside
Pole Orientation
Why do some work better than others?
Influences
Why do some work better?
Magnetic field strength is proportional to the number of turns of wire per unit length and the strength of current passing through
The tighter the coil, the stronger the field
When the magnet loses contact with the coil, the circuit is interrupted
Friction is not dominant drag force, the induced currents are
Conclusion
Conclusion
In 1820 it was demonstrated that a magnetic compass needle can be deflected by an electric current
Moving electrical charges produce a magnetic field
In this experiment, we learnt a lot about how electricity and magnetism are linked, and how each can create the other