Editing Copper Tube and Magnet

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Physics]]:
| Magnets, Induction
|-
| Grade Range:
| [[Middle School]], [[High School]]
|-
| Format:
| [[Hands-on]]
|}

Induction is a more advanced topic for students to try to understand, so this demonstration is intended for an advanced science class.

== Materials ==

* Copper Tube
* Two Neodynium Magnets
* A soft surface to drop onto, if possible

== Safety Precautions ==


==Demonstration==

# Show the tube and magnet to the students. Drop the magnet from waist height onto a soft surface to show that it is a normal magnet. Ask the audience to identify what makes the magnet fall to the ground.
# Have a volunteer come up, and give them a magnet. Hold the second magnet and the copper tube, and ask the class if dropping the magnet through the tube will speed it up, slow it down, or not do anything. Show that the tube isn’t magnetic by holding both magnets against it.
# On the count of three, have yourself and the volunteer drop your magnets. When you drop yours through the tube, it will slow down! Depending on the tube’s dimensions, it can take between a couple seconds to a minute for the magnet to fall through. With our smaller tube, the magnet will drop through it in about five seconds.

==Why This Works==

''Magnetic Induction'' Is a relationship property between magnets and charge. A moving magnet can induce, or generate, a charge in a conductive material. Copper is conductive, but it is a non-magnetic metal. This means we can have a charge move through copper, and the metal won't stay magnetized from it. However, a moving charge will induce, or generate a magnetic field around itself, in contrast to a magnet generating a charge. In this demonstration, we can see that we are generating a charge in the copper because the magnet slows down. Gravity is pulling the magnet downward, and as it moves it is inducing a charge in the copper tube. This charge, however, is ''also'' moving, at the same speed as the magnet, and so it will induce a magnetic field which ''counters'' the magnet's field! The induced magnetic field provides a strong counter force, but it isn't strong enough to fully resist the force of gravity. It does, however, slow the magnet's descent by a large fraction!

==Additional Information==
* If possible, get a set of different copper tubes to compare the speeds that the magnets fall at.
* This demonstration pairs well with the [[Do it Yourself Electromagnet]].