# Homework Help: Question regarding radius of circular paths (chapter the nucleus)

1. May 19, 2005

### Sanosuke Sagara

I have my doubt,solution and question in the attachment that followed.Thanks for anybody that spend some time on this question.

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• ###### Doc 4 (the nucleus).doc
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2. May 19, 2005

### Dr.Brain

OK the problem with your solution is that You have made it a bit too complicated.
First of all ,
After accelerating through a potential , the electrons gain certain amount of K.E , which can be calculate din the following way:

$eV= \frac{1}{2}mv^2$

From The KE , calculate velocity gained by the electron beam.

Now if you have studied how charged particles behave in magnetic fields, you should know that electrons when enter prependicular to a magnetic field, start moving in a circle.

Force due to a Magnetic field on an electron provides the centripedal force necessary for moving in circle. therefore,

$F= -e(VxB) = m \frac{v^2}{R}$

From here calculate the radius of the beam...easy ..isnt it?

3. May 20, 2005

### Sanosuke Sagara

Yes,Dr Brain.Thanks for your help and I really appreciate it.Thanks again for your explaination in detail.