## GR9277 #69 light

kolndom
Posts: 19
Joined: Tue Oct 25, 2005 11:29 am

### GR9277 #69 light

Would some one help me out of this tough problem? Thank u in ad

GR9277#69. A fast charged particle passes perpendicularly through a thin glass sheet of index of refraction 1.5. The particle emits light in the glass. The minimum speed of the particle is __

I think another problem I failed to solve is similar. Would some one help me solve this problem as well? Thank u in ad

A fast charged particle passes perpendicularly through a thin glass sheet of index of refraction 1.5. The cone of Cerenkov light, emitted in the glass at angle seta, is incident on the glass-air interface at the critical angle for total reflection. The speed of the particle is __

danty
Posts: 19
Joined: Fri Sep 30, 2005 6:40 pm
When a charged particle penetrates in a dielectric material, with speed greater the the speed of light in the dieletric it emmits light. The phenomenon
is called Cerenkov radiation. So the minimum speed of the particle must be c/n=c/1.5

This question is far from being considered a trivial one, and in cases like this cannot understand the perception of the test makers.