Magnetic-field present pass through cardboard, air, and certain other materials, relying on whether they"re permeable or nonpermeable. Test various materials to see which conference magnetic present of force and also act together magnetic shields, and which allow magnetic currently of pressure to pass with them.

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Three ceramic donut magnets (rectangular magnets will also work)Two piece of cardboard of same size, around 2 x 2 3/4 customs (5 x 7 centimeters)Two pencils, 2 3/4 in (7 cm) or longerFive or six document clipsWood handmade stick, plastic straw, or any other nonmetallic materialSteel butter knifeHot-glue gun and also glue (alternatively, you have the right to use rubber bands)
First, do a cardboard-pencil sandwich: affix the pencils to one item of cardboard, place the pencils parallel to every other and also close to the opposite edge of the cardboard. Glue the 2nd piece that cardboard to the pencils so that you finish up through a cardboard-pencil-cardboard sandwich.Add two more magnets on peak of the very first one so that they are held in place by magnetic attraction. Don"t glue them!

Hold your shielding sandwich v the magnets top top top. Raise the paper clips one in ~ a time come the bottom next and notice what happens. The file clips should be attractive to the magnet and so will certainly hang indigenous the bottom of the cardboard sandwich.

As you add more record clips, an alert what happens. If you include them carefully, they will certainly arrange themselves so that they room evenly spaced.

Insert the craft stick or plastic straw into the shielding sandwich, move it around, and an alert what happens. The paper clips have to be unaffected.

Now insert the flat blade the a stole butter knife right into the shielding sandwich, move it from next to side, and notification what happens. Do the paper clips fall off? try experimenting with various materials, together as various metallic coins. Make a perform of the products you test and note what happens.


What"s going On?


The magnetic-field lines from the magnet pass v the cardboard, the air, and also other products like the craft stick and also straw. Products that allow magnetic lines of pressure to pass through them are dubbed nonpermeable since magnetic fields do not kind within them.

In contrast, the steel knife acts together a magnetic shield, an interpretation the force lines comes from the pole the the magnet perform not pass v it. Instead, they space gathered in, travel down the metal strap, and also re-enter the magnet at the other pole. Materials that conference magnetic lines of force are claimed to be permeable, because they support the development of magnetic areas within those materials. Only magnetic materials are permeable.

The photos listed below show the effect of a nonpermeable product (at left) and permeable material (at right) on magnetic present of force in ours cardboard sandwich.


Going Further


Try using only one or 2 magnets. Together the magnetic field strength it s okay weaker, it gets harder to save the file clips from falling. How can you modify the sandwich to do a weaker magnet occupational better?

Insert an open up pair of steel scissors in between the pieces of cardboard, then close the scissors together if cut the ar lines. The file clips will certainly drop off once the ar lines connect with the close up door scissors.

Scientists design magnetic forces using field lines. A compass present up follow me a field line, therefore you have the right to trace ar lines with a compass.

Iron filings also line up along field lines. By sprinkling steel filings on a piece of document placed on optimal of a magnet (or a pair of magnets), you have the right to see the field lines. Our Snack, Magnetic present of Force, demonstrates this phenomenon.

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Field lines come native the phibìc pole that a magnet and also return come the southern pole. Magnets have field lines the exert a force on magnets or iron. If there room no field lines, there is no force, and the result is magnetic shielding.