Distance of closest approach

[Fallen Seraph]

In an electromagnetics question I've been asked to calculate the distance of closest approach of an alpha particle which collides with a lead nucleus, but I've never come across the concept of the distance of closest approach. My book is mute on the subject and google yields nothing but more questions on the matter. What does it be exactly?

[Dick]

You didn't say what information you were given. I suspect you are given KE of the alpha and can assume it is fired directly at the lead nucleus. In that case what is the KE when the nucleus stops it and where did the KE go?

[Fallen Seraph]

Oh I ask not for an answer or even a method. My apologies if I was unclear. I'm just unacquainted with the concept of distance of closest approach, and was wondering if I could become acquainted with it?

[Dick]

Isn't "distance of closest approach" self explanatory? Maybe I don't understand your non-question? Can you be more specific?

[andrevdh]

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/rutsca2.html

[Fallen Seraph]

Ah right. There we go. Thanks a lot for that.