Here is a concise summary of the content:
**Title:** Experimenting with a Van de Graaff Generator
**Key Points:**
1. **Machine Overview**: A Van de Graaff generator creates high DC voltages (up to 200,000+ volts) between its dome and ground, stored in its capacitance.
2. **Voltage Limitation**: The voltage can only rise to a point where the charge leakage equals the charge input due to the repelling force between similar charges.
3. **Sharp Edges**: Charges accumulate and leak faster from sharp edges, reducing voltage and arc size.
4. **Safety**: Despite high voltages, the experimenter experiences less pain due to:
* Lower body resistance (5 kΩ) when exposed to high voltage, bypassing skin resistance.
* Faster discharge of the machine's capacitance (100x smaller than a Leyden jar).
5. **Demonstrations**:
* Charging a Leyden jar wirelessly through the air.
* Attracting and repelling objects (paper, ground ball) based on charge and shape.
* Hair-raising experiments showcasing voltage changes.
6. **Principle Explanations**:
* Charge attraction and repulsion.
* Effect of shape (pointy vs. flat) on charge accumulation and leakage.
Here are the key facts extracted from the text, numbered and in short sentences:
**Machine and Voltage Facts**
1. The machine creates super high DC voltages.
2. The voltage is stored in the machine's capacitance, between its top dome and the earth/ground.
3. The voltage of the dome can exceed 200,000 volts.
4. The voltage would rise higher if the tower were taller, farther from conductors, and in a vacuum.
**Charge and Discharge Facts**
5. At any voltage, charges start to escape into air molecules or as single electrons.
6. Higher voltages result in more charges leaking due to stronger repelling forces.
7. The voltage can only rise to a point where leaking charges equal incoming charges.
8. Charges accumulate more in sharp edges, leading to faster discharge.
**Human Body and Electricity Facts**
9. Human body resistance is around 5 kilo-ohms under high voltage, but measured resistance is higher (~100 kilo-ohms to 1 mega-ohm) due to skin resistance.
10. High voltage can easily break through thin, dry skin.
11. Arcs can short from the dome to the body, spreading through low-resistance tissue under the skin.
**Specific Experiment and Measurement Facts**
12. The capacitance between two domes is approximately 15 picofarads.
13. The Leyden jar's capacitance is around 1.5 nanofarads, 100 times larger than the machine's.
14. The machine's discharges are faster (hundred times) due to lower capacitance.
15. A 200 kilovolt discharge through a 5 kilo-ohm body would result in a 40 amp spike of current.
**Observations and Demonstrations**
16. A flame (plasma/ionized gas) can be both attracted and repelled by a charged point.
17. A neutral object (e.g., paper, ball) can bounce between two charged objects due to alternating attraction and repulsion.
18. A grounded body can discharge the dome's voltage, causing attraction to disappear.
19. Paper with a flat face up can become overcharged and fly away, while paper with edges exposed can be attracted without arcing.