Feynman's apparent paradox - Electromagnetism

Click For Summary

Discussion Overview

The discussion centers around Feynman's "apparent" paradox related to electromagnetism, specifically addressing the implications of a rotating disc powered by a battery that stops supplying current. Participants explore the paradox's relation to the conservation of angular momentum.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant describes the paradox as presented in Feynman's Lectures, highlighting the conflict between the expected rotation of the disc and the conservation of angular momentum when the current ceases.
  • Another participant asserts that there is no paradox, suggesting that the electromagnetic field itself can possess angular momentum, which may resolve the apparent conflict.

Areas of Agreement / Disagreement

Participants express differing views on whether the situation constitutes a paradox, with one arguing for the existence of a paradox and another claiming it does not exist due to the role of the electromagnetic field.

Contextual Notes

The discussion does not resolve the implications of the electromagnetic field's angular momentum or its relationship to the conservation laws in this context.

Shan Ravi
Messages
11
Reaction score
0
Feynman's "apparent" paradox - Electromagnetism

This is the paradox discussed in chapter 17 of "Feynman Lectures on Physics - Vol II"

http://www.flickr.com/photos/37453425@N07/3447068420/

Say suppose the battery drains out or somehow you stop the current outta the battery. By electromagnetic laws, the disc ought to rotate... but then that violates the law of conservation of angular momentum (since no external torque is being applied)

I suggest you read the "apparent" paradox in the book.
 
Last edited by a moderator:
Physics news on Phys.org


No paradox, the electromagnetic field can have angular momentum.
 


Ooh... thnx :)
 

Similar threads

Graduate A paradox in electromagnetic theory
  • · Replies 56 ·
2
Replies
56
Views
25K
Graduate Feynman's Paradox: Solving the Mystery of the Rotating Disk | Solution Revealed
  • · Replies 12 ·
Replies
12
Views
11K
Graduate How do you make the potential zero at infinity, here
  • · Replies 9 ·
Replies
9
Views
4K
Graduate An Alternative Model of the Double Slit Interference Experiment
  • · Replies 24 ·
Replies
24
Views
25K