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1 Physics question. DESPERATE FOR HELP!?
3.A scuba diver uses his waterproof flashlight to shine a beam of light so that it strikes the surface of the water at an angle of incidence θi. Use Snell’s law to find the angle of incidence that would give an angle of refraction for the refracted ray to be directed right along the surface, and show that θi is the same as the critical angle for total internal reflection.
1 Answer
- peterpanLv 77 years ago
sinθi/sinθr=nr/ni
then
sinθi=(nr/ni)sinθr
if the refracted ray is directed along the surface the ray is ortogonal to the normal to the surface
so
θr=π/2
sinθi=nr/ni
θi=arcsin(nr/ni)
where
ni=1.33 [water]
nr=1 [air]
then
θi=arcsin(1/1.33)=48,75 degrees
the critical angle is when there is no refration, refraction ray ortogonal to the surface normal [θr=π/2]
sinθi=(nr/ni)sinπ/2
sinθi=(nr/ni)
that is excatly the condition considered above
