# Static Electricity Simulator - Triboelectric Series, Electroscope, Paschen Law, Thunder Distance

> Triboelectric series, electroscope induction animation, charge sharing between spheres, Paschen breakdown and spark length, corona at points, thunder distance.

- URL: https://qilingtools.com/en/physics/electrostatics
- Category: Physics Tools (https://qilingtools.com/en/physics)
- Tags: [Physics](https://qilingtools.com/en/tags/physics), [Education](https://qilingtools.com/en/tags/education)
- Last updated: 2026-10-29
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

Pick two materials (fur, glass, silk, hair, PVC, PTFE and more) and the rubbing animation shows which way electrons move and which ends up positive or negative. The electroscope page walks through charging by induction in five steps: bring the rod near, ground, remove ground, remove the rod, with the leaves opening and closing; it also computes charge sharing between two connected spheres. The breakdown page uses Paschen’s law for air at any pressure and gap, estimates spark length, Van de Graaff maximum voltage and corona at sharp points. The lightning page turns flash-to-bang time and air temperature into storm distance, with the 30–30 rule and typical lightning numbers.

## How to use

1. On the triboelectric tab choose materials A and B, press Rub to watch electrons transfer, then Separate
2. On the electroscope tab press Next step to see how it ends up with the opposite charge to the rod
3. Set the radii and charges of two spheres and press Connect to see charge redistribute and energy lost
4. On the breakdown tab adjust pressure and gap to read the breakdown voltage on the Paschen curve; shrink the tip radius to see corona start
5. On the lightning tab press the button at the flash and again at the thunder to get the storm distance

## Features

- Triboelectric series of 24 materials with a rubbing and charge-transfer animation
- Five-step electroscope induction animation with a negative rubber or positive glass rod
- Charge sharing between connected spheres: charges, common potential, surface fields and energy loss
- Paschen curve for air: breakdown voltage and average field for any pressure and gap
- Spark length estimate, Van de Graaff maximum voltage and a Peek’s-law corona demo
- Flash-to-bang timer with temperature-corrected speed of sound, 30–30 rule and typical lightning values

## FAQ

### How do I read the triboelectric series?

The series runs from materials that readily lose electrons to those that readily gain them. When two are rubbed together, the one higher in the list loses electrons and becomes positive, the lower one gains them and becomes negative, and the farther apart they are, the stronger the charging tends to be. Glass rubbed with silk becomes positive; rubber rubbed with fur becomes negative. The ranking is empirical, and humidity, contamination and how you rub all change the result.

### Why does induction leave the electroscope with the opposite charge?

When a charged rod comes near, free electrons in the metal are pushed away or pulled closer, so the near end gets the opposite charge and the far end the same charge as the rod. Grounding lets the like charge (or the matching electrons) flow to earth. Remove the ground first and then the rod, and the remaining opposite charge has nowhere to go, spreads over the electroscope and opens the leaves. The rod never touches and loses none of its charge.

### What voltage breaks down air?

In a uniform field at atmospheric pressure air breaks down at about 3 MV/m (3 kV/mm), roughly 30 kV across 1 cm. More precisely, Paschen’s law says breakdown depends only on the product of pressure and gap pd, with a minimum (a little over 300 V for air) below which breakdown gets harder again. Near sharp points or across long gaps the field is non-uniform and discharges grow as streamers and leaders at average fields far below 3 MV/m.

### Why do sharp points discharge first, and what does a lightning rod do?

A conductor is at the same potential everywhere and the surface field of a sphere is E = V/R, so the smaller the radius of curvature, the stronger the field. Sharp points exceed the corona onset field (Peek’s law) first and ionize the air. A lightning rod does not drain a storm cloud to prevent strikes; it launches the first upward leader as a downward leader approaches, giving the strike a defined low-resistance path, and its down conductor and ground electrode carry the current safely to earth.

### How do I tell how far away lightning is?

Light arrives almost instantly while sound travels about 343 m/s in 20 °C air, so distance ≈ 343 × seconds: about 3 s per kilometre or 5 s per mile. If the gap between flash and thunder is under 30 seconds, the storm is within about 10 km and you are in strike range, so get inside a building or hard-topped vehicle. Wait 30 minutes after the last thunder before going out: that is the 30–30 rule.

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