Van de Graaff Generator

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Van de Graaff Generator
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Goals

• Learn how a Van de Graaff generator works and
  what it is used for
• Explain demonstration/experiments that involve
  the Van de Graaff generator

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What is it?

• The Van de Graaff generator is a device that
  separates electric charges mechanically.
• This produces a high voltage with a low current.

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Safety

1. Do not allow students to use the Van de Graaff
   generator unsupervised.
2. People with cardiac pacemakers should never
   operate the generator or come in contact with it.
   
3. Obviously, we are dealing with high voltage here.
   Stay about three feet away from the collector
   while it is charged.
4. Always discharge the collector dome between
   experiments and when you are finished.
5. The motor produces a lot of heat that could
   damage the belt or the motor itself. Do not run
   the generator continuously for long periods of
   time.
6. Leave the upper and lower combs alone.
7. Keep the entire device clean and dry.
8. Handle the aluminum parts with care.

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How much voltage?

• Voltage isis commonly used as a short name for
  electrical potential difference
• Which means is a measurement of the energy
  contained within an electric field, or an
  electric circuit, at a given point
• This VdG generator can produce anywhere from
  10-200 thousand volts (V).
• It is safe because the current is quite low.

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What does it look like inside?
Metal Sphere
Insulating tube
Conveyor belt (rubber)
Metal Combs
Base (Electric motor)
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How does it work?

• The VdG generator is a charge separator.
• When turned on, the belt begins to move, picking
  up negative charges deposited by the metal comb
  at the base.
• The belt then transfers the charges to the metal
  comb at the top of the generator.
• The metal comb is attached to the metal sphere
  and thus transfers the negative charges to the
  sphere.

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How is the VdG like the cashiers check out at
the grocery store?
Think of the groceries as charges.
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Metal Sphere
Insulating tube
Base (Electric motor)
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What is it used for?

• Used during early research into radioactivity and
  atomic structure, used as power source for
  particle accelerators.
• Still used to power high energy x-ray machines
• Useful in laboratory study of electrostatics

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VdG Experiments

1. Sparks!
2. Shock Line
3. Crazy Hair
4. Flying Cereal
5. Light off, light on.
6. Flying Fur
7. Anyone for Pie?

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Questions

• Explain in your own words how the VdG generator
  works.
• 2. Explain in words and using a diagram how
• Someones hair can stand up
• How a shock can occur
• How something can be repelled by the VdG