Magnetism

Objective:

The objective of this lab is to learn about Magnetism and its effects on everyday life

Background on

If something is said to be magnetic it means that it has the extraordinary power to attract or repel other materials to itself. Things we normally associate with magnets are most commonly ferromagnetic materials, the most common ones are iron, nickel, cobalt and their alloys (mixtures of those different materials). Although ferromagnetism is responsible for most of the effects of magnetism encountered in everyday life, all other materials are influenced to some extent by a magnetic field created by several other types of magnetism. 

Paramagnetic substances such as aluminum and oxygen are weakly attracted to an applied magnetic field; diamagnetic substances such as copper and carbon are weakly repelled. While antiferromagnetic materials such as chromium and spin glasses have a more complex relationship with a magnetic field.  The force of a magnet on paramagnetic, diamagnetic, and antiferromagnetic materials is usually too weak to be felt, and can be detected only by laboratory instruments, so in everyday life these substances are often described as non-magnetic. 

Magnetism, at its root, arises from two sources: electric current and by Spin magnetic moments of elementary particles (such as electrons). An electric current is a flow of electric charge. In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionized gas (plasma). Think about the spin of electrons generating a magnetic moment like the orbit of an arm on a fidget spinner where the north and south poles would be where you hold your fingers and the electrons would be the holes in each arm, the faster they spin the stronger the magnetic field.

Magnetic fields and magnets in general are really neat, but they can also be really useful. Magnets are used in electric generators to turn mechanical energy into electricity, while some motors use magnets to convert electricity back into mechanical work.  Electrically-powered magnets in cranes grab and move large pieces of metal, some weighing thousands of pounds. MRIs use powerful magnetic fields to generate a radar-like radio signal from inside the body, using the signal to create a clear, detailed picture of bones, organs and other tissue. A pocket compass uses a magnetic needle to show which way is north.

Materials

• Magnet (does not have to be super strong, a fridge magnet will work)
• Needle
• Styrofoam cup bottom (use an Exacto knife to cut the bottom of the cup off, keep the top for a future experiment)
• Post-it arrow stickies
• Plastic sample cup
• Modeling clay
• Toothpick
• Water
• Tape

Method

Prepare Experiment

• Grab all materials needed for the experiment and set them up in front of you in a neat and organized manner

Run Experiment

1. Using modeling clay make a small mountain in the center bottom of their sample cups
2. Place a cut toothpick into the center of the mountain
3. Add water just near the top of the toothpick, but not submerging it
4. Create the compass platform
5. Place the north arrow on the circle, then place the needle with points lined up on top of that, then tape the needle onto their circle. *Note: very important the needle is fully taped down for the next step
6. Take turns rubbing the edge of a magnet along the needle 30 times (take the edge of the magnet and rub it along the needle from the eye to the point then do it again until it has been done 30 times)
7. Gently add the compass platform to the cut toothpick by pressing its center onto the toothpick, but do not press it through
8. Test their compass and show how magnets can affect their movement

Analyze Data

Does your compass move on its own toward magnetic north? What could be keeping your magnetic compass from working properly if you are inside?

Conclusions

Magnets are a part of everyday life in first world countries. That being said it is hard to escape an electronic device that does not have some sort of magnet in it. Magnets are very useful in many different ways. Without the magnetic field generated by the core of our earth we would not be alive or would be very different from the way we have evolved under the protection of Earth’s magnetic field.

Make It Your Own

Can you change the compass needle to a nail and have the same outcome? What if you used a galvanized or aluminum nail does the outcome change?

Extension Activities to do at home

Try using your compass at home especially near older computers, does your needle tend to point towards the old computer or to magnetic north? One thing to keep in mind is that many older computers use very strong magnetics for the different drives that they have. These magnets can be very strong and would definitely mess with your compass. Now try the same thing with something like a laptop, in these systems magnets may still be used but are much small and should have very little effect on the compass you have made.