AIM OF THE EXPERIMENT: To show how charged particles make a sound.MATERIALS: scissors, a ruler, plasticine, a large metal paper clip, something woollen: a scarf, a coat or a jumper of one hundred per cent wool, a clear plastic sheet.
METHOD: RESULTS: A crackle is heard.
WHY? Electrons pass from the wool onto the plastic. They gather together until their combined energy is enough to carry them across the air gap from the wool to the paper clip. The movement of the electrons through the air creates sound waves, and that is why the crackle is heard. Cut a strip from the sheet (3 cm x 20 cm).
Use the plasticine to fix the paper clip to the table so that it stands upright.
Wrap the wool round the plastic and pull the plastic quickly through the cloth. Do this three times.
Quickly bring the piece of plastic up to the top of the paper clip.