Apparatus
Demo #1: Glass rod rubbed against silk cloth
- Test tube: this works well as a glass rod which gives off electrons when rubbed against a piece of silk cloth (can be found in any lab)
- Scarf: make sure the scarf is made of silk
- Paper: once the glass rod is charged from the rubbing, it can now pick up neutral material such as a SMALL piece of paper (the charge is not great enough to pick up larger pieces)
Demo #2: Comb rubbed against hair
- Comb: as you comb your hair, electrons from your hair move onto the comb, giving it a net negative charge
- Hair: hair has a greater ability to give up electrons compared to a comb as ranked by the triboelectric series (materials ranked in order of their ability to hold or give up electrons)
- Pepsi bottle: drill a small hole at the bottom center of the bottle and have water running through it like a steady flow from the tap. Water, which is neutral, will bend as a charged object (comb) is played next to it. Note that placing food coloring in the water will make the bending effect much more visible
Demo #3: Hair raising
- Van de Graff: spread your hand on the output dome of the VDG. Upon turning the generator on, the dome, which is positively charged, will attract to the electrons from your body, causing your hair to stand up
- Plastic stool: plastic is a good insulator; therefore, standing on the plastic stool will insulate yourself from the ground (causing charges to build up)
Demo #4: Electric spark
- Van de Graff: while the VDG is running, place a metal object (conductor) near it
- Metal wrench: this can be found in any tool box. Electrons from the wrench will “jump” across onto the surface of the dome, creating as electric spark followed by a crackling sound
