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Magnitude and Direction of induced voltage

  • #1
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Homework Statement


Hey everyone I have a physics e&m question: [/B]
http://blob:https%3A//www.physicsforums.com/aa779f37-be23-43d7-a888-d70263a3854b
upload_2016-5-3_1-7-6.png


Homework Equations




The Attempt at a Solution



upload_2016-5-3_1-7-31.png

I took the derivative to find the magnitude of the induced voltage. (do I need to add a constant c?)
I am having trouble with the direction of the current flow though... Do I use the right hand rule?

Thanks![/B]
 

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  • #2
Simon Bridge
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I took the derivative to find the magnitude of the induced voltage. (do I need to add a constant c?)
I am having trouble with the direction of the current flow though... Do I use the right hand rule?
The constant "c" is usually either the speed of light in a vacuum or the constant of integration ... do either of these situation apply here?
The current flow is determined by the right hand rule in conjunction with a law of physics that applies to induced currents.
I'm puzzled you started at (c) ... did you do (a) and (b)?
 
  • #3
andrevdh
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4 a) Does the question ask for the magnetic (flux) ?

Oh, it should read the magnitude, not magnetic!

Shouldn't you use Faraday's law?
 
  • #4
Simon Bridge
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  • #5
andrevdh
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There might be a small gap in the lower right-hand part of the loop
 
  • #6
Simon Bridge
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Well spotted - there may well be.
 
  • #7
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Sorry! Yeah I meant magnitude.
 
Last edited:
  • #8
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Okay so the derivative of magnetic flux is the induced voltage. I am having trouble calculating flux. Flux = BA cos (theta). How do I get the area....?
 
  • #9
Simon Bridge
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What shape is the area in question?
 
  • #10
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Ahh I forgot that they gave us the length of the square. I think I was able to get it.
13149837_10208152309959848_930633277_n_zpsdro9gsiq.jpg

Does this look right?
 
  • #11
Simon Bridge
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in (c) and (d) the flux density is different in different parts of the square, how did you account for this?
(hint: the variable y should not be in your answer)
in (b) the question asks for the direction of the current
 
  • #12
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For b) I say it is counterclockwise. My reasoning is that the field is decreasing as time passes (e^(-t)). The field will want to come out and the way to do that is for the induced current to flow counterclockwise.

I am not clear on c). Doesn't the y variable account for the different flux values for different y values?
 

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