Advance Preparation
and Setup

If at all possible, set up the materials so the students can hook up the earphone with alligator clips, so soldering will be unnecessary. However, the alligator clips may not make good contact with the fine magnet wire, so solder a few pieces of bell wire on to the ends of the magnet wire. Then screw an alligator clip to each end of the wires from the plug. Many stores with electronics departments sell several kinds of inexpensive portable AM radios. If you have the students use personal stereos, you must provide stereo plugs, with one wire soldered to the output of one channel and the other wire soldered to the ground. If you do not have an amplifier/speaker for each group, set up a station with an audio amplifier and speaker. Experiment in advance to find out which input jack works (tape, phono, auxiliary) works best with the cup microphone and the solar cell. Try to position the station under a fluorescent light, with an incandescent light nearby for comparison. If you can provide an oscilloscope so students can view the output of the audio amplifier, so much the better (see Background Information).

Solar cells are fragile. Consider gluing the solar cell to a piece of wood or plastic (after you have soldered the wires to the cell). If the solar cell has wires attached, fasten these down for strain relief (so the wire will not break off inside the cell). It is necessary to solder very fine wires to the cell, and this is an awkward and time-consuming job. Other cells come with leads attached.