Maxwell’s Fourth Equation: Moving electrical charges (fields) generate magnetic fields AND changing magnetic fields generate electrical fields (electricity). We're going to do a couple of experiments to illustrate both of these concepts.
Magnetic fields are created by electrons moving in the same direction. A magnetic field must come from a north pole of a magnet and go to a south pole of a magnet (or atoms that have turned to the magnetic field.) Iron and a few other types of atoms will turn to align themselves with the magnetic field. Compasses turn with the force of the magnetic field.
If an object is filled with atoms that have an abundance of electrons spinning in the same direction, and if those atoms are lined up in the same direction, that object will have a magnetic force.
Materials: magnet wire, nail, magnet, compass, 12VDC motor, bi-polar LED, D-cell battery, sandpaper [am4show have='p8;p9;p10;p37;p92;' guest_error='Guest error message' user_error='User error message' ] Wrap wire around a nail and connect to power to create a simple electromagnet that can pick up paper clips.
Or you can make a galvanometer: wrap your wire around a toilet paper tube and remove the tube after you’ve got 30+ turns of wire around it. Hook up the ends of the wire to a battery and place a compass through the middle of the coil. The needle should move when you energize the coil!
Connect a standard LED to the terminals of a 12DC motor and give the shaft a spin. The LED will light up! Why is that? There is a permanent magnet and an electromagnet (coil of wire) inside the motor. When you spin the shaft, you are essentially waving a permanent magnet past the coil of wire. The two ends of the coil wire are connected to the motor terminals, which are connected to the LED. You have just made an electric generator.
A "going further" experiment: You can make a second galvanometer and connect it to your first one, and then wave a magnet through the inside of one of the coils and watch the compass move inside the other! What’s going on here? The same as previously, only this time the magnet is being passed through (back and forth) one coil, which generates electricity in the wire and powers the second coil and turns the second coil into a magnet (as indicated my movement with the compass near the second coil).
How does this work? Since many electrons are moving in one direction, you get a magnetic field! The nail helps to focus the field and strengthen it. In fact, if you could see the atoms inside the nail, you would be able to see them turn to align themselves with the magnetic field created by the electrons moving through the wire.
Find out more about this key principle in Unit 10.
[/am4show]
Magnetic fields are created by electrons moving in the same direction. A magnetic field must come from a north pole of a magnet and go to a south pole of a magnet (or atoms that have turned to the magnetic field.) Iron and a few other types of atoms will turn to align themselves with the magnetic field. Compasses turn with the force of the magnetic field.
If an object is filled with atoms that have an abundance of electrons spinning in the same direction, and if those atoms are lined up in the same direction, that object will have a magnetic force.
Materials: magnet wire, nail, magnet, compass, 12VDC motor, bi-polar LED, D-cell battery, sandpaper [am4show have='p8;p9;p10;p37;p92;' guest_error='Guest error message' user_error='User error message' ] Wrap wire around a nail and connect to power to create a simple electromagnet that can pick up paper clips.
Or you can make a galvanometer: wrap your wire around a toilet paper tube and remove the tube after you’ve got 30+ turns of wire around it. Hook up the ends of the wire to a battery and place a compass through the middle of the coil. The needle should move when you energize the coil!
Connect a standard LED to the terminals of a 12DC motor and give the shaft a spin. The LED will light up! Why is that? There is a permanent magnet and an electromagnet (coil of wire) inside the motor. When you spin the shaft, you are essentially waving a permanent magnet past the coil of wire. The two ends of the coil wire are connected to the motor terminals, which are connected to the LED. You have just made an electric generator.
A "going further" experiment: You can make a second galvanometer and connect it to your first one, and then wave a magnet through the inside of one of the coils and watch the compass move inside the other! What’s going on here? The same as previously, only this time the magnet is being passed through (back and forth) one coil, which generates electricity in the wire and powers the second coil and turns the second coil into a magnet (as indicated my movement with the compass near the second coil).
How does this work? Since many electrons are moving in one direction, you get a magnetic field! The nail helps to focus the field and strengthen it. In fact, if you could see the atoms inside the nail, you would be able to see them turn to align themselves with the magnetic field created by the electrons moving through the wire.
Find out more about this key principle in Unit 10.