Does Shaking Harder Create More Charge in a Faraday Flashlight?

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Discussion Overview

The discussion revolves around the mechanics of charge generation in a Faraday flashlight, specifically whether the amount of charge produced is influenced more by the speed of the magnet's movement or the number of passes it makes through the coil. Participants explore the relationship between coil length, number of turns, and the energy conversion process involved in this system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that both the speed of the magnet and the number of passes contribute to the amount of charge generated, likening the process to pumping water.
  • One participant questions whether a single pass through a longer coil could produce the same amount of charge as multiple passes through a shorter coil.
  • Another participant emphasizes that the number of turns in the coil is a key parameter, suggesting that the total charge is roughly proportional to the number of passes multiplied by the number of turns.
  • There is a proposal that inverting the coil and allowing the magnet to fall could convert gravitational potential energy into electrical energy, indicating a relationship between coil length and energy output.

Areas of Agreement / Disagreement

Participants express differing views on the primary factors influencing charge generation, with no consensus reached on whether speed or number of passes is more significant. The discussion remains unresolved regarding the specific mechanics involved.

Contextual Notes

Participants mention complexities such as leakage flux and the need for equal turn density when comparing coil lengths, indicating that assumptions about the system's behavior may vary.

Tweaked9107
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So I have a very basic question, but I have next to no electrical understanding so can't answer it myself.

With a Faraday torch you shake a magnet in a coil to create electrical charge. They say the harder you shake the more charge you create, so my question is this... is it the increased number of passes the magnet makes through the coil that would create more charge, or is it the speed of the magnet passing through the coil that creates more charge?
 
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Its a bit of both - but basically (mostly) each pass of the magnet moves a set amount of charge from one place to another. It's like pumping water.
Note: no charge is created or destroyed in this process.
 
Thanks for the reply.

So do you think a single pass through a 1m long coil could produce the same amount as multiple passes through a 0.1m long coil?
 
Tweaked9107 said:
Thanks for the reply.

So do you think a single pass through a 1m long coil could produce the same amount as multiple passes through a 0.1m long coil?

The number of turns, not the length is the key parameter. There are complexities such as leakage flux, but in a rough sense yes. The number of passes times the number of turns should be roughly proportional to the amount of charge.
 
You can imagine if you just inverted the coil+magnet, allowing the magnet to fall - then the setup converts a proportion of the gravitational potential energy into electrical energy stored in a battery. Twice the coil length (all else i.e. the turn density remaining equal) gets you twice the GPE ans so twice the electrical energy.
This would be the same if you just shook it horizontally - bearing in mind you'll also need twice the effort.
 

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