Van de Graaff Generator
A stylized electrostatic generator integrates belt-delivered charge onto a dome modeled as a capacitor with C proportional to radius (isolated-sphere cartoon). Voltage V = Q/C rises until a user threshold mimics air breakdown; a brief spark partially discharges the dome with a cooldown to avoid rapid re-triggering.
Who it's for: High-school and intro college electrostatics; complements the Coulomb field visualizer and plasma-ball toy.
Key terms
- electrostatic induction
- breakdown field
- capacitance
- Van de Graaff
- spark
Live graphs
How it works
A rubber belt driven by rollers carries charge toward a metal dome. Charge accumulates on the dome (modeled as a capacitor whose value grows with radius) until the electric field is large enough for **air breakdown** — then a stylized spark jumps to a grounded electrode and the dome partially discharges.
Key equations
Frequently asked questions
- Are the voltages in kilovolts?
- No: the plot uses a relative model with an adjustable breakdown threshold. Real Van de Graaff machines can reach megavolts; always follow institutional safety rules around high voltage.
- Why does a larger dome radius lower the voltage for the same charge?
- With the simple C ∝ R scaling used here, a larger capacitance means less voltage for the same stored charge. That matches the qualitative idea that larger conductors “hold” charge at lower surface fields for the same charge.
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