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Proof Plane 20mm Dia
Proof Plane 20mm Dia (Product Code: SLE/EAM/14) is a small circular metal plate on an insulating handle, used in electrostatics to pick up a sample of charge from a conductor and carry it to a detector. As the smallest plate in a range of three sizes, it is suited to sampling charge from small areas, for example when comparing different parts of a charged Van de Graaff dome. It is one of the simple but important physics lab instruments made by Jain Scientific Equipments Pvt Ltd (ScienceLab) in Ambala, India.
Specifications
| Parameter | Detail |
|---|---|
| Plate | Circular metal plate, 20 mm diameter |
| Handle | Insulating |
| Purpose | Transferring charge and investigating charge distribution in electrostatics |
| For use with | Van de Graaff generator |
| Other sizes in the range | 40 mm and 60 mm diameter plates |
Typical Use
Holding the proof plane by its handle, the student touches the plate against a charged conductor, lifts it away and brings it to the cap of an electroscope or into a Faraday's pail; the size of the response shows how much charge the plate collected. Repeating this at a sharply curved region and at a flatter region of the same conductor reveals that charge gathers more densely where the surface curves most, which is the principle behind lightning conductors and the point discharge seen on a Van de Graaff generator.
The 20 mm plate is the choice when you want to sample a small, well-defined patch of surface; the larger plates in the range collect more charge and give a bigger deflection. Always discharge the plate by touching it to earth between samples, hold it only by the handle, and keep the handle clean and dry, since grease or damp air lets charge leak away and spoils electrostatics results.
Manufacturer
ScienceLab proof planes are made by Jain Scientific Equipments Private Limited, a manufacturer of electrostatics and general physics apparatus based in Ambala, Haryana. The company profile explains more about the firm and its range.
Related Electricity and Magnetism Equipment
A proof plane needs a charge source and a detector; these items complete the set:
- Van de Graaff Generator — the charged conductor the proof plane is designed to sample.
- Van De Graaff Accessory Kit — includes a Faraday's pail and other items for electrostatics demonstrations.
- Electroscope, Gold Leaf — shows the charge carried by the proof plane through leaf deflection on a scale.
- E-Field Detector — indicates the sign and size of charge with an LED array.
For more electrostatics apparatus, browse Electricity and Magnetism.
Frequently Asked Questions
What size is this proof plane?
The plate is 20 mm in diameter. The same design is also available with 40 mm and 60 mm plates.
Which plate size should I choose?
Choose the 20 mm plate to sample small areas and compare charge density at different points; larger plates pick up more charge and give a stronger signal on the detector. Many labs keep more than one size.
What equipment is it used with?
It is intended for use with a Van de Graaff generator, together with a detector such as an electroscope or a Faraday's pail.
Why do my results fade on humid days?
Moisture or grease on the insulating handle allows charge to leak. Keep the handle clean and dry, and work in the driest part of the room.
Is it supplied singly or in a set?
The pack quantity is not stated on this page. Please tell us how many you need through our contact page and we will confirm.
Can you supply schools in bulk or overseas?
Yes. ScienceLab quotes class and institutional quantities for India and international markets; include your delivery location in the enquiry.
Request a Quote
For pricing on the Proof Plane 20mm Dia, or a mix of plate sizes, contact us through the contact page or add it to the enquiry cart with your electrostatics apparatus.
Last updated: 24 September 2026
