The rods are made of plastic, stainless steel, bronze, brass, aluminium and copper, so the copper has a conductivity billions of times better than the plastic. So you get much larger currents induced in the rods, which of course produce a magnetic field and hold up the magnet, slowing its drop.
There are several batteries which apply a voltage, and you can complete various different circuits by holding the contacts. With some friends you can make more. You can make parallel circuits, explore resistance and connect batteries in different orientations.
The Exhibit measures the sub microamp currents and causes a flow of leds (like in christmas lights) proportional to this current.
It is often hard to visualise electric current because it is invisible, these sticks let you see the electric current flowing by creating a flow of lit LEDs like some christmas tree lights. They can detect the very small currents (microamps) that flow through your body when you touch both ends of an AA battery.
You can use them to show the difference between series and parallel circuits in a really visual way.
This is a classic, simple demo that is surprisingly hard to do, because it is hard to hold a very brittle, thin propelling pencil lead without it breaking.
This setup is machined with a groove between the two stainless steel pillars that is completely in line, so that there are no bending forces on the lead, so it reliably doesn't break.
This is a very standard piece of physics (Biot-Savart law) which Dave had always assumed was important but not strong enough to simply experience yourself. On the offchance while in the lab with some magnets he had a go, and it works rather beautifully. Turn on the current one way and the wire jumps to the left and then back again with the opposite current.
This is probably the simplest generator that can produce a noticible amount of power, and is used in the torches you shake to power them.
There are two LEDs on each coil, one will light if the induced current is clockwise and the other if it is anti-clockwise. One will flash as the north pole move into the coil and one as the south pole does.
Though it is a classic, it has got a lot more effective with the introduction of rare earth magnets. You can investigate how the voltage produces is affected by where the magnet is moved, how fast it is moved, how strong the magnet is and how many turns the coil has.
To make the experience more intuitive this version visualises the flow of electricity with a flow of led lights.
It is one of the most effective exhibits we have ever built, and even if you know what is going to happen it is somehow still surprising whether you are a 2 year old, or a physics grad.
