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PFStudent
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Homework Statement
7. In Fig. 28-35, an electron accelerated from rest through potential difference [tex]{V}_{1} = 1.00{\textcolor[rgb]{1.00,1.00,1.00}{.}}kV[/tex] enters the gap between two parallel plates having separation [tex]d = 20.0{\textcolor[rgb]{1.00,1.00,1.00}{.}}mm[/tex] and potential difference [tex]{V}_{2} = 100{\textcolor[rgb]{1.00,1.00,1.00}{.}}V[/tex]. The lower plate is at the lower potential. Neglect fringing and assume that the electron’s velocity vector is perpendicular to the electric field vector between the plates. In unit-vector notation, what uniform magnetic field allows the electron to travel in a straight line in the gap.
http://img228.imageshack.us/img228/4953/platepicgl6.jpg
Homework Equations
[tex]
{\vec{E}}_{p1} = {\frac{\vec{F}_{21}}{q_{2}}}
[/tex]
[tex]
{\Delta{V}_{p}} = {-}{\int_{r_{0}}^{r_{1}}}{\vec{E}_{p1}(r)}{\cdot}{d{\vec{r}}}
[/tex]
[tex]
{\vec{F}_{B}} = q{\vec{v}}{\times}{\vec{B}}
[/tex]
The Attempt at a Solution
Ok, this problem does not seem that hard, however the wording isn’t really clear. So let me see if I understand this problem, you have an electron being accelerated by [tex]{V}_{1}[/tex] into an electric field produced by two plates. Where the bottom plate has potential [tex]{V}_{2}[/tex].
Ok, so my question is if the bottom plate has potential [tex]{V}_{2}[/tex], does the top plate have a potential?
Also, what about the electric field between the two plates how can you tell in what direction the electric field points in?
Any help is appreciated.
Thanks,
-PFStudent
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