- #1
theowne
- 14
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Homework Statement
An electron initially at rest is accelerated through a potential difference of
V and directed into a region with 1) two parallel plates separated by 20 mm with
a potential difference of 20 V between them and 2) a uniform 0.5 T magnetic field
which is parallel to the plates. (a) Calculate the minimum V required such that the
electron feels no force as it moves through the region between the plates. (b) Why is
this just a minimum?
Homework Equations
Fm= qvb
Fe=qE
The Attempt at a Solution
My initial thought was that the magnetic force and electric force would oppose each other and we could solve qE = qvB for v and thus the delta V required to accelerate to V. However then it asks why is this a minimum. But I don't think it could work if it was just a minimum because increasing v would increase and give an excess magnetic force, so the electron would feel a force, leading me to think this reasoning is wrong.
Could I get some advice for this? For example, it says the electron is directed into the region, does that means its moving parallel to B?