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c_m
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Homework Statement
Ok here it goes...
A stream of electrons, each with speed u = 5.9 x 10^6 m s^-1 and traveling along the x-axis in the positive x-direction enters a region pervaded by a uniform magnitic field B. The electrons the describe a circle with raidus R in the horizontal xy-plane, circulating anticlockwise as viewed from above.
With varius questions i have calculated the...
1)the direction of B is in the -Z direction
2)Magnitude of B = 1.7 x 10^-3 T
Now for the part i have become brain dead on...
Two large, parallel, metal plates 0.20m apart and placed symetrically on either side of the incoming electron beam, are now used to apply a uniform electric field in the region where the electrons were circulating.
This electric field is such that the electron beam is no longer deflected but continues straight on in the original positive x-direction.
My question is:
1)Starting from the Lorentz force Law and using Newtons first law, How do i determine the direction of the electric field (E)?
Homework Equations
Lorentz Force Law in a uniform field
F = q[E + u x B
B=magnetic field
q=charge on electron
u=speed of electron
E = electric field
The Attempt at a Solution
Now i assume that i need to find the magnitude of the electric field, so when i rearranged Lorentz Law this is what i ended up with:
qE = B x q x u
But when i input my values going by the units which are:
T x C x m s^-1 this gives me Newtons
where i know the units of electric charge should be N C^-1
So obviously i have gone very wrong somewhere probably with my magnitude expression??
Please help, if you need any more details, let me know and i will try and supply them.
Cheers in advance