1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Drag in a Dynamo

  1. Sep 2, 2010 #1
    I was wondering;

    Imagine two situations:

    1) I rotate an axle with a strong magnet attached within a conductive coil (a dynamo).
    2) I rotate an axle with a strong magnet attached without a conductive coil.

    Does the presence of a coil (and therefore the generation of current in the coil) add any drag to the rotary mechanism, or is the dynamo simply harnessing a form of energy potential that would have been lost otherwise?
  2. jcsd
  3. Sep 2, 2010 #2
    Traditionally, it's called "back EMF"
    Conceptually, one can consider the well established fact that the generation of electricity(actually, movement) with a mechanical generator REQUIRES resistance to that generation.
    That is, in ALL cases of mechanical electrical generators, there will be an opposing force.
    If it were not the case... Free Energy!!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Drag in a Dynamo
  1. Linear dynamo - how to (Replies: 1)