We did a few different activities today. I had out the snap circuits and had students build a series circuit with 2 light bulbs and then use the same light bulbs in a parallel circuit. A series circuit is bascially one big loop. The current flows from the battery and through each lamp in turn before returning to other end of the battery. In a parallel circuit, the current splits up and some goes to each lamp separately. If one of the lights fails, in the parallel circuit the other light will still light up because you still have a closed circuit. But in the series circuit, if one bulb breaks, then the circuit is open and currently can’t flow through the loop.
To show students that an electric field can also make a light bulb glow, I put an old fluorescent bulb near a plasma toy and parts of it would light up, as seen in the photo below.
Lastly we made mini motors with 28 gauge copper magnet wire. Wind 15 to 20 loops around the end of a fat marker to make a coil, leaving about 10 cm of wire on either end of the loop. Take the ends of the wire and wrap them around the sides of the loop once or twice to hold it together, then take sandpaper and rub off the insulation on the wire sticking out from the coil.
You need to get the insulation off so the wire can make a good electrical connection with the paper clips. Paper clips are bent so they can support the coil and are taped withelectrical tape, to each end of a battery (C or AA work fine). Place a magnet under the coil loop and then give the coil a flick and if you have everything positioned just right it will keep spinning – see the video below. I got this lab from Teaching Physics with Toys. I used this book a lot when my boys were younger.
It can take some fussing to get this to work right. You have to make sure the insulation is off the ends of the wire and you want it to be pretty close to the magnet. If you have a variety of magnets you might test to see which ones work best and how close the coil loop needs to be to the magnet to keep it spinning. This class is small enough that I let them take home the mini motors if they wanted to.
This is the last class til after winter break.