1. The problem statement, all variables and given/known data Hi 1) I read the following article: http://pdg.lbl.gov/2005/reviews/passagerpp.pdf On page 12 of the .pdf there is a figure, figure 27.8, which shows how a charged particle deviates from it's path when scattered by the Coulomb force that comes from the nuclei of the matter in the bubble chamber. I don't understand the figure. I know I am supposed to use formula 27.15 (my teacher told me), but I don't get the geometry in figure 27.8 - the bold line is the particle's trajectory and the whole grey area is the matter it is moving it (the bubble chamber). S_plane - which I must find - is the distance between the trajectory and the "dotted" line - but what does the dotted line represent? 2) When talking about Coulomb-forces; if an electron in a bubble-chamber gets near a nuclei in the champers matter (lets say hydrogen, H_2). Then does the hydrogen-atom attract the eletron? And vice versa - if a proton gets near the H_2-nuclei, does it get repelled? Do the particles have to pass next to the nuclei or can it be outside the atom? These were my two questions. I hope you can help me, thanks.