- #1
michaelw
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http://www.vaxop.com/pic.GIF is my little picture
what is drawn is a magnetic field pointed N to S (left to right)
the helical path shown is the path of an electron taken in that field
my question is, why is that so?
at the far left, the magnetic field is ~constant, and according to the RHR, the electron (which has a parallel and perpendicular velocity component) will have its perpendicular component moved clockwise
then the magnetic field decreases as u approach the center.. here's where i get confused.
since its decreasing, the electron will move in a way to increase the magnetic field to the right (lenz's law) and thus will continue to move clockwise (is this right?? or is the movement just determined by the magnetic field already present)
then the magnetic field increases towards the right
the electron will move to counter this, and induce a magnetic field of its own pointing to the left.. thus it *should* move counter clockwise (but this isn't what's seen in the diagram)
where is my thinking flawed?
I remember if you have a closed wire, and you move it into a magnetic field, there will be a magnetic field created to oppose the magnetic field, thus current will run clockwise (if the original magnetic field is out of the page, the induced will be into the page) and the opposite is true if the flux is decreasing..
shouldnt the same thing be happening here?
also, as the magetic field increases, what will happen to the radius and the magnitude of the velocity perpendicular to the field? since Fb = qvB = ma, acceleration obviously must change, but a = mv^2/R. so will the velocity change, or the radius? or will changing the velocity induce a change the radius? or will a changing radius induce a change in velocity? (by change in, i mean change in magnitude)
this is quite confusing..
what is drawn is a magnetic field pointed N to S (left to right)
the helical path shown is the path of an electron taken in that field
my question is, why is that so?
at the far left, the magnetic field is ~constant, and according to the RHR, the electron (which has a parallel and perpendicular velocity component) will have its perpendicular component moved clockwise
then the magnetic field decreases as u approach the center.. here's where i get confused.
since its decreasing, the electron will move in a way to increase the magnetic field to the right (lenz's law) and thus will continue to move clockwise (is this right?? or is the movement just determined by the magnetic field already present)
then the magnetic field increases towards the right
the electron will move to counter this, and induce a magnetic field of its own pointing to the left.. thus it *should* move counter clockwise (but this isn't what's seen in the diagram)
where is my thinking flawed?
I remember if you have a closed wire, and you move it into a magnetic field, there will be a magnetic field created to oppose the magnetic field, thus current will run clockwise (if the original magnetic field is out of the page, the induced will be into the page) and the opposite is true if the flux is decreasing..
shouldnt the same thing be happening here?
also, as the magetic field increases, what will happen to the radius and the magnitude of the velocity perpendicular to the field? since Fb = qvB = ma, acceleration obviously must change, but a = mv^2/R. so will the velocity change, or the radius? or will changing the velocity induce a change the radius? or will a changing radius induce a change in velocity? (by change in, i mean change in magnitude)
this is quite confusing..
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