How Can I Demonstrate Electric Forces Using a Van de Graaff Generator?

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Discussion Overview

The discussion centers on demonstrating electric forces using a Van de Graaff generator, with a focus on creating a practical setup that allows for the manipulation of lightweight charged objects through controlled electric fields. Participants explore various demonstration ideas and seek visual and impactful methods for showcasing electric forces.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant suggests using a naked CRT to demonstrate electric forces, explaining how electrons are accelerated by electric fields generated by high voltages, though notes the safety concerns regarding high voltages.
  • Another participant emphasizes the need for a visual demonstration that involves movement, prompting a request for refinement of existing ideas.
  • A link to a resource from Scientific American is provided, which may contain relevant demonstrations involving static electricity.
  • Additional videos are mentioned as potential sources of inspiration for demonstrations, though specific content is not detailed.

Areas of Agreement / Disagreement

Participants generally agree on the need for a visual and impactful demonstration but do not reach a consensus on a specific method or approach. Multiple ideas and resources are presented without resolution on the best option.

Contextual Notes

Safety concerns regarding high voltages in demonstrations are noted, indicating a limitation in the practicality of certain proposed methods. The effectiveness of the suggested resources and videos remains unverified within the discussion.

Who May Find This Useful

Individuals interested in physics demonstrations, educators seeking engaging methods to illustrate electric forces, and those exploring experimental setups involving electric fields may find this discussion relevant.

RossMiller
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I need to perform a demonstration of electric forces. Something more substantial than weak static charge forces would be best. Could someone please help me by describing a practical way for me to put a charge onto something lightweight and then generate an electric field to move it back and forth. A way to make an electric field that has a variable and easily controlled magnitude and direction is what I am looking for. Thanks.
 
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RossMiller said:
I need to perform a demonstration of electric forces. Something more substantial than weak static charge forces would be best. Could someone please help me by describing a practical way for me to put a charge onto something lightweight and then generate an electric field to move it back and forth. A way to make an electric field that has a variable and easily controlled magnitude and direction is what I am looking for. Thanks.

Welcome to the PF.

One demo would be to show a naked CRT and explain how the electrons are boiled off of the cathode at the base of the neck, and accelerated through the electron gun lenses in the neck and out to the anode/face of the CRT. It's the electric field of the lens elements and the high + voltage of the anode surface that accelerates the electron beam enough to light up the phosphors coating the inside of the face at the anode. Pretty impressive acceleration!

One downside of this demo is that a naked CRT can expose some pretty high voltages, depending on how you package the demo. If you guard all the HV generating circuitry, the anode button and the neck endcap are pretty well insulated.

EDIT -- The x-y deflection of the electron beam to paint the picture on the CRT face is done with magnetic fields generated by currents in the deflection yoke, but the acceleration of the beam toward the face/anode of the CRT is all due to the electric fields generated by the high voltages in the electron gun and on the anode.
 
Here are a few more videos that might inspire you.




 
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