Electromotive force and trigonometry

Click For Summary

Discussion Overview

The discussion revolves around the application of Faraday's law of electromagnetic induction, specifically focusing on the expression for electromotive force (emf) in relation to trigonometric functions. Participants explore the implications of using sine versus cosine in the context of time-dependent magnetic flux and its differentiation.

Discussion Character

  • Technical explanation, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant presents Faraday's law and derives an expression for emf, suggesting it should involve sine instead of cosine when applying limits.
  • Another participant agrees with the initial claim under the assumption that certain variables do not depend on time.
  • A different participant questions whether the derivation is purely calculus-based, implying a potential misunderstanding of the mathematical approach.
  • Another participant notes that the choice of sine or cosine is arbitrary due to the nature of phase shifts in trigonometric functions.

Areas of Agreement / Disagreement

Participants express differing views on the correct trigonometric function to use in the expression for emf, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Limitations include assumptions about the independence of variables and the arbitrary nature of the time point chosen for analysis, which may affect the interpretation of the results.

mcastillo356
Gold Member
Messages
666
Reaction score
365
TL;DR
Contradictory result
Faraday's law:
\epsilon=-N\dfrac{\Delta{\phi}}{\Delta{t}}=-N\dfrac{\Delta{(BA\cos{\theta})}}{\Delta{t}}=-N\dfrac{\Delta{(BA\cos{(\omega t)})}}{\Delta{t}}
Applying calculus
\epsilon=NBA\omega\cos{(\omega t)}
Shouldn't it be \epsilon=NBA\omega\sin{(\omega t)}, just if I apply limits?
Thanks
 
Physics news on Phys.org
Assuming A,B don't depend on t, I think you are right!
 
  • Like
Likes   Reactions: mcastillo356
There is only one way: if t_0=NBA\omega. But this is not calculus. Or yes?
 
The point of t=0 is generally arbitrary, it doesn't matter if your angle follows a sine, a cosine, or anything else with a constant phase shift.
 
  • Like
Likes   Reactions: mcastillo356
Thanks, mfb!
 
Thank's, Math_QED
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 11 ·
Replies
11
Views
3K
Replies
6
Views
2K
Replies
12
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
Replies
9
Views
2K
Replies
4
Views
2K