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


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9 Responses to “Maxwell’s Fourth Equation”

  1. It has to do with the properties of the magnet. Magnets are usually made from iron, nickel, or cobalt (these are elements from the periodic table), and as to why those create a magnetic field, you’ll find a lot of information and videos on that in Unit 11. You can learn what causes magnetism here.

  2. jocelyn lin says:

    i still dont know how magnet can actually stick with other magnets because a fluffy teddy bear and another fluffy teddy bear
    does not stick together does it depend on their microorganism? cause im still not sure about why magnets can also attract a lot of magnets?

  3. Yes, not all motors are going to work for this experiment as they don’t generate enough power to turn on the LED. The one I used int he video is a 12V motor from Radio Shack. Good idea using a drill to power it!

  4. Hi there,

    Made a great electromagnet with the kids but can’t manage to make the led turn on with a 12VDC motor. I made it come on weakly attached to a power drill but that was the best I could do. Is the RPM or amp important (11,800, 0.8. Also, our motor looks a lot bigger than the one in the video)?

    Thanks

  5. Hmmm… it should be working with a 12V motor. Did you spin the shaft in both directions? The only reason to have the bi-polar LED is so that it will light up when the shaft is spun in either direction.

  6. Carla Cove says:

    We are using a 12V motor.

  7. What size motor are you using? You’ll need larger one that most 3V hobby motors.

  8. Carla Cove says:

    our LED is not lighting up. We don’t have a bi-polar LED. Is that why?

  9. Sophia Zimmer says:

    This is TOTALLY WICKED!!! Thanks so much!