a person walking by.Ī fly stick is a miniature, battery powered Van de Graaff generator. Have someone hold onto the large sphere while blowing soap bubbles with a wand, the bubbles will become positively charged and will be attracted to anything that is grounded e.g. Tape streamers to your volunteer, like an extra-long moustache! Place a piece of fake fur on the large sphere, the individual fur strands will stand.
Without removing the grounding rod, ask the volunteer to put one hand on the dome, the other hand by their side and make sure they understand not to move their hands until you tell them to.Ask a student to step up onto the insulated stool.
#Cg society floor generator generator
This can be repeated by placing a metal pie panplate (or three!) on top of the generator and repeating the steps above.Take the ground away, and the Styrofoam peanuts will fly off the generator.Without removing the grounding rod, place Styrofoam peanuts (or confetti) on top of the large sphere.Ground the dome by touching the grounding rod to it.Move the small sphere around the sphere in different positions so that everyone can see the sparks.Ask a student to turn off the lights to make it easier to see the sparks. Take the small sphere away and let a charge accumulate on the dome.Slowly turn the knob clockwise so the motor turns the belt.Touch the small sphere (connected to the ground wire) to the dome.Warn students they may get small shocks which will scare them more than hurt them. Although the Van de Graaff generator produces a very low current, it may cause problems with people who have heart problems or a pacemaker. Safety note: Make sure you ground the large sphere after each use by touching it with the ground wire or small sphere. Why did your teacher ground the generator before allowing the volunteer to step off the stool? What caused a shock when the volunteer touched a fellow student?
Why doesn’t the hair come down after the machine has been turned off? As long as the person is standing on an insulated platform, the electrons will not be able to travel down to the ground and their hair will remain standing up.Įxplain how static charge causes materials to attract or repel each other.Ī Van de Graaff Generator (available at Arbor Scientific) They are most obvious in a person's hair because the like charges of the electrons repel each other and cause the hairs to stand up and spread away from each other. When a student puts a hand on the sphere, the electrons will spread out onto that person as they repel from the other electrons. When the negative charges on the peanuts repel the negative charges on the generator, the peanuts push off the sphere. The electrons that collect on the sphere spread out into the Styrofoam peanuts and confetti, making the little, light objects negatively charged. Putting Styrofoam peanuts or confetti on top of the Van de Graaff generator can create a cool trick. It doesn't take very much current to light a fluorescent bulb! Flowing electrons result in an electrical current, lighting up the light tube. When a fluorescent light tube approaches the negatively charged generator, the electrons on the generator flow through the tube and the person holding it. If we bring the grounding rod close enough to the large sphere, the electrons rip through the air molecules in order to jump onto the grounding rod, creating a spark and crackling noise. It provides a convenient path for electrons to move to the ground. The grounding rod is a smaller sphere, attached by a wire to the Earth. The Earth has lots of room for electrons to spread out upon, so electrons will take any available path back to the ground. These electrons repel each other and try to get as far away from each other as possible, spreading out on the surface of the sphere. Van de Graaff experiments are all based on the fact that like charges repel.Ī Van de Graaff generator pulls electrons from the Earth, moves them along a belt and stores them on the large sphere. You know that it makes peoples' hair stand on end, but do you actually know how it works? Most people have seen a Van de Graaff generator before at a science centre or on TV.
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