So my outreach activities are taking on a new twist, thanks to the discovery that with £50, a clever engineer and a tech who loves to solder, you can make a baaaaaby magnetometer for the kids to play with and learn a bit about magnetic fields.
Attached to that bit of blue breadboard are a magnetoresistive (MR) sensor, a couple of 9 V batteries, a few simple components, and a pair of light-emitting diodes (LEDs). In the picture above, we've got a power supply hooked up instead of batteries, but we'll switch to the batteries once we put the board into a nice plastic box so that it won't be damaged. The MR sensor is about the size of a penny and can be waved around freely on the end of its cable. For a bit of pretty illustration, the LEDs light up alternately depending on the polarity of the field, and you can get them to switch if you pass a permanent magnet next to the sensor.
All we have to do is hook up a multimeter to measure the voltage and the kids can use the sensor to measure the Earth's magnetic field. I've written a 4-page lab script that gets them to measure it on a unit circle horizontally (to find North) and vertically (to find the magnetic dip). I think it's pretty easy to follow, but the test run won't be until next month so I'll refrain from posting a PDF until I'm certain that 16-year-olds can really do it.
Our lab is awesome, no?