laser beam of dia=D strikes at theta.i an n.t=1.5 glass pane. what is the diameter of the beam in the glass... i started by setting up a geometric interpretation of the phenomena and concluded that the light would remain columned and both sides of the beam would simply shift from theta.i to theta.t, where n.t*sin(theta.t)=n.i*sin(theta.i). However, we are covering some of the physical interpretations of optics, such as dispersion and optical path lengths. Considering I'm only 3 weeks into my upperdivision optics class, what aspect of electromagnetic theroy would I introduce into this problem if any? Is it a trick question?... I doubt that. Thanks for any help.