Analysis of Rectangular Loop in Uniform Magnetic Field

Click For Summary

Homework Help Overview

The discussion revolves around the analysis of a rectangular loop dropped into a uniform magnetic field. The loop has specific dimensions and properties, including mass, resistance, and orientation in relation to gravitational forces. Participants are examining the induced electromotive force (emf) and the resulting current, as well as the dynamics of forces acting on the loop as it interacts with the magnetic field.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants are discussing the induced emf and current in the loop, questioning the correctness of the original poster's method and equations. There are inquiries about the forces acting on the loop as it enters the magnetic field and how to determine the direction of the induced current using Lenz's law. Some participants express confusion over the clarity and completeness of the original post.

Discussion Status

The discussion is ongoing, with participants providing feedback on the original poster's equations and reasoning. Some guidance has been offered regarding the application of Lenz's law and the implications of the loop's dimensions. There is a recognition of the need for clarity in the original post to facilitate effective assistance.

Contextual Notes

There are concerns about the implications of using an infinite length for the loop and how it affects the calculations. Participants are also noting the importance of maintaining a clear reference to previous posts for continuity in the discussion.

Ganesh
Messages
13
Reaction score
0
What happens when a rectangular loop is dropped into a field of uniform, magnetic field B extending to infinity?
The loop has a mass m and its resistance is R.
It has length L, breadth b, L tending to infinity.
Gravity is present in downward direction.
The loop is dropped such that emf is induced across one breadth.


Emf induced = Bvb
Current = Bvb/R.
Force net = mg - Bvb*b*B/R
accn = dv/dt = g - B^2vb^2/mR
Integrating an expression in log is obtained which does not match the reqd answer given in a book.

Is the method correct?
 
Last edited:
Physics news on Phys.org
What are the forces on the loop as it enters the field region? How can you deduce the direction of induced current in the loop as the flux linking it changes dynamically? Hint: use Lenz's law.
 
Oh you seem to have put some equations now...lemme see.
 
I just edited myn post now
 
maverick280857 said:
What are the forces on the loop as it enters the field region? How can you deduce the direction of induced current in the loop as the flux linking it changes dynamically? Hint: use Lenz's law.

aaaaaaaaaaaaaaaa
 
I did just that.
 
The loop consists of 4 segments: 2 of length L and 2 of length b. Each segment carries the same current.

Note: I do not understand so many a's in your last post. Please do not waste our time and resources (no offence meant). I obviously made that post before you put up the equations (before which you seemed to be unable to start correctly...now you're finishing incorrectly!).

Cheers
Vivek
 
Since l is infinite, the second side of bredth b never enters the field.
Also, the force on each of the sides of infinite length is equal and opposite.
So net force is the expression I typed out.
 
Look if you're going to keep changing your original post, we'll have no reference to see and its pointless helping you!

Remember to post your complete reasoning and solution on PF before asking for help.

Cheers
Vivek

EDIT: If L (and not l) tends to [tex]\infty[/tex] then as you have correctly reasoned, it shouldn't directly appear in the expressions though I would've preferred to use some finite L and eventually let it go to infinity if possible. Of course that isn't the question we're doing now.

Appears fine (except the first form)...will post in detail later.
 
Last edited:
  • #10
I have written all the equations I know.
Is the application correct?

P.S. I did not know you had typed out replies before I had finished editing (which I did immediately after my post came up)
 

Similar threads

Derivation Of Torque On Current Loop Due To Uniform Magnetic Field
  • · Replies 4 ·
Replies
4
Views
2K
Induced current and force on circular loop in varying magnetic field
  • · Replies 4 ·
Replies
4
Views
2K
Direction and magnitude of electric field produced by current change
  • · Replies 8 ·
Replies
8
Views
2K
Making sense of sequence of ideas in MIT OCW's 8.02 notes on Faraday
  • · Replies 1 ·
Replies
1
Views
2K
Magnetic energy density, self-inductance of coaxial cylindrical shells
  • · Replies 10 ·
Replies
10
Views
2K
Induced EMF in a moving Loop Conductor
  • · Replies 3 ·
Replies
3
Views
3K
Understanding the math of definition of electromotive force
  • · Replies 1 ·
Replies
1
Views
1K
How Does Induced Current Change with Loop Acceleration Through a Magnetic Field?
  • · Replies 8 ·
Replies
8
Views
2K
Magnetic field affecting a circular loop
  • · Replies 1 ·
Replies
1
Views
2K
Force on rectangular loop by a current in a long straight wire
  • · Replies 4 ·
Replies
4
Views
3K