Maxwell’s Third Equation: Invisible magnetic fields exert forces on magnets AND invisible electrical fields exert forces on objects. A field is an area around a electrical, magnetic or gravitational source that will create a force on another electrical, magnetic or gravitational source that comes within the reach of the field. In fields, the closer something gets to the source of the field, the stronger the force of the field gets. This is called the inverse square law.
Materials: balloon, magnet, small objects like paper clips or iron filings
[am4show have='p8;p9;p10;p37;p92;' guest_error='Guest error message' user_error='User error message' ] To see how magnetic fields exert forces, play with a couple of magnets or place a magnet in a test tube and then in a bed of iron filings. Do you see the magnetic field? If you don't have iron filings, try noticing where on the magnet paper clips attach. Can you figure out where the lines of force occur?
Now let's take a look at invisible electric fields. Notice how your hair sticks up when you build up a static electrical charge. You can build up a charge on dry days by scuffing along the carpet in socks, rubbing your hair with a balloon, sliding down a plastic slide, or by rubbing a fluorescent bulb with a wool sweater or plastic bag. Bring these charged items next to a pile of paper shreds or packing peanuts (or even a ping pong ball on a smooth, flat surface) and you’ll find the objects follow the charged object when placed near an electrical field.
Find out more about this key principle in Unit 10.
[/am4show]
Materials: balloon, magnet, small objects like paper clips or iron filings
[am4show have='p8;p9;p10;p37;p92;' guest_error='Guest error message' user_error='User error message' ] To see how magnetic fields exert forces, play with a couple of magnets or place a magnet in a test tube and then in a bed of iron filings. Do you see the magnetic field? If you don't have iron filings, try noticing where on the magnet paper clips attach. Can you figure out where the lines of force occur?
Now let's take a look at invisible electric fields. Notice how your hair sticks up when you build up a static electrical charge. You can build up a charge on dry days by scuffing along the carpet in socks, rubbing your hair with a balloon, sliding down a plastic slide, or by rubbing a fluorescent bulb with a wool sweater or plastic bag. Bring these charged items next to a pile of paper shreds or packing peanuts (or even a ping pong ball on a smooth, flat surface) and you’ll find the objects follow the charged object when placed near an electrical field.
Find out more about this key principle in Unit 10.