Electromagnetic Induction and Waves

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Homework Help Overview

The discussion revolves around a problem involving electromagnetic induction, specifically focusing on a circular loop placed in varying magnetic fields. The loop's dimensions and resistance are provided, and participants are tasked with determining the induced electromotive force (emf), current, and direction of the current for a specific case.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between magnetic flux and induced emf, questioning how to compute the magnetic flux (Φ) given the available information. There is confusion regarding the use of equations and the physical meaning of Φ.

Discussion Status

The discussion is active, with participants seeking clarification on the definitions and relationships involved in the problem. Some guidance has been provided regarding the interpretation of the magnetic field depicted in the diagrams, and the rate of change of the magnetic field has been identified as relevant information.

Contextual Notes

Participants express uncertainty about the magnetic field's presence and its implications for calculations. There is an emphasis on understanding the parameters given in the problem, including the rate of change of the magnetic field, which is crucial for solving the problem.

jlmessick88
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Homework Statement


The figure shows a 10-cm-diameter loop in three different magnetic fields. The loop's resistance is 0.10 ohm.

http://i63.photobucket.com/albums/h148/jlmessick88/jfk_Figure_P25_12.jpg

For case (a), what is the induced emf?
ε = mV

For case (a), what is the induced current?
I = mA

For case (a), what is the direction of the current?
clockwise
counterclockwise
no current

Homework Equations



ε = |ΔΦ/Δt|
Εcoil = N * |ΔΦpercoil /Δt|


The Attempt at a Solution


No idea :(
Any...ANY help would be great!
Thanks!
 
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You've given an equation for the induced emf in terms of the change of "Phi" with time. What physical quantity is Phi? Based on the answer to that question, how would you compute it?
 
that's where i was getting confused...i wasn't sure if there was some way i could solve for "phi" given the info...
if that's not the correct equation then where do i begin??!?
 
I didn't say it wasn't the correct equation.

There is a way for you to solve for Φ using the given information. If you knew what Φ was, then you would have known that. So, answer my first question first please. What is Φ?
 
well i couldn't used the equation Φ= ABcos() b/c i don't have a magnetic field...
i couldn't use ε = |ΔΦ/Δt| b/c even if i made it become ε = pi * r^2 |ΔB/Δt| b/c i still don't have a magnetic field
 
What you mean you don't have a magnetic field? A magnetic field is depicted in each of the three diagrams, and its rate of change is given.
 
oh! ok...so ...for the change in magnetic field and time, i would just create the change over some period of time determined by myself correct??
 
Not really necessary. The rate of change for the leftmost case is given as half a tesla per second

So you know that if the time interval (change in elapsed time) is 1 s, then the change in magnetic field will be +0.5 T.

Can you see that this is a way of saying (in words) that:

ΔB = 0.5 T

Δt = 1 s

 

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