What is the maximum induced emf in a rotating coil generator?

Click For Summary

Homework Help Overview

The discussion revolves around calculating the maximum induced electromotive force (emf) in a rotating coil generator, specifically focusing on the parameters of the magnetic field, coil dimensions, and rotation frequency.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply the formula for induced emf but questions the validity of their approach, particularly regarding the angle theta and the application of the equation for rectangular loops to a circular coil.
  • Some participants question the understanding of the change in magnetic flux over one complete revolution and seek clarification on the net change in flux.
  • Others suggest considering the nature of the flux change and its implications for the induced emf.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the flux change and its relationship to the induced emf. Some guidance has been offered regarding the nature of flux change during rotation, but no consensus has been reached on the correct approach to the problem.

Contextual Notes

Participants are navigating the complexities of applying the emf formula to a circular coil and are addressing potential misconceptions about the behavior of magnetic flux in relation to coil rotation.

sona1177
Messages
171
Reaction score
1

Homework Statement


In a rotating coil generator, the magnetic field between the poles of an electromagnet has the magnitude .40T. A circular coil between the poles has 120 turns and radius 4.0 cm. The coil rotates with frequency 5Hz. Find the maximum emf induced in the coil.


Homework Equations


Emf= change in magnetic flux/time



The Attempt at a Solution


Emf=change in magnetic flux/time=NBAcosθ/time. need emf max, so theta=1??
Emf max=NBA/time
Frequency = 1/t
so t =1/Frequency=1/5=.20

N,B, and A are all given in the problem (A = pi r^2). I plugged the numbers into my equation and got 1.21 but that is wrong.

I have used this equation for rectangular loops, why isn't it working here and how do i do it?

thanks
 
Physics news on Phys.org
what do you mean by theta = 1?
 
you need to calculate total flux change/total time in one revolution.

can you tell me what should be the net change in flux in one complete revolution?
 
The change of flux is zero in one revolution. The magnitude of emf is equal to the time derivative of the flux.

ehild
 
Doesn't the flux through the area encompassed by the coil peak twice per revolution?
 

Similar threads

EMF induced by a magnet falling through a coil
  • · Replies 4 ·
Replies
4
Views
3K
Why is the value of EMF generated by a generator not zero at t = 0 s?
  • · Replies 2 ·
Replies
2
Views
2K
Induced current in a square coil by a current-carrying wire
  • · Replies 2 ·
Replies
2
Views
2K
Calculate the induced EMF of a rotating loop
  • · Replies 7 ·
Replies
7
Views
3K
Magnet moved in a circular coil
  • · Replies 10 ·
Replies
10
Views
2K
Induced EMF graph of a very small wire moving through a coil
  • · Replies 3 ·
Replies
3
Views
3K
Induced EMF in a coil outside a solenoid
  • · Replies 15 ·
Replies
15
Views
7K
High School EMF induced by Bar Magnet falling through a Coil
  • · Replies 3 ·
Replies
3
Views
2K
Why wouldn't rotating the handle 90 degrees induce an EMF?
  • · Replies 3 ·
Replies
3
Views
1K
AC generator -- Understanding coil voltages as function of position
  • · Replies 1 ·
Replies
1
Views
2K