Proton in a magnetic field

  • Thread starter oh.rry21
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  • #1
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Homework Statement



I have a circular magnetic field and a proton (A) a distance Ra from the center of the circle. The magnetic field is traveling into the page and is decreasing at some rate B(t). I have the radius of the circle Rb.

The question is that when the proton is released, what happens to the proton?

Homework Equations



F = qv x b
Right Hand Rule

The Attempt at a Solution



I'm pretty sure that with a changing magnetic field, it will create an induced current/magnetic field that will exert a force on it. Its not a mathematical problem necessarily i just need to know what happens to the proton. in the midst of a changing magnetic field.
 

Answers and Replies

  • #2
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is the proton moving?
 
  • #3
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well i assume it starts as stationary because the problems says "when the proton is released". so no i dont think theres a velocity vector to it.
 
  • #4
Doc Al
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The changing magnetic field will create an electric field (induced EMF).
 
  • #5
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so the induced EMF (E) will exert a force on the proton F=qE then?

So... i use faraday's law to determine the E and just multiply it by q?
 
  • #6
Doc Al
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so the induced EMF (E) will exert a force on the proton F=qE then?

So... i use faraday's law to determine the E and just multiply it by q?
Right. But as soon as it starts moving there will be a magnetic force on the proton as well.
 
  • #7
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so at the end of the day.

the induced emf (the E field) will exert a force on the proton, but as the proton moves, there will be a magnetic force on the proton (cross product of its velocity and the magnetic field)?

in terms of vectors then...can i expect it to move wherever the resultant of the summed E and B field vector?
 
  • #8
Doc Al
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so at the end of the day.

the induced emf (the E field) will exert a force on the proton, but as the proton moves, there will be a magnetic force on the proton (cross product of its velocity and the magnetic field)?
Sounds good.

in terms of vectors then...can i expect it to move wherever the resultant of the summed E and B field vector?
You can expect that the net force on it will be the vector sum of the electric and magnetic forces.
 

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