1. what best describes the critical angle?

Question

a. The angle an incoming light beam makes with the normal

b. The angle a reflected light beam makes with the normal

c. The angle a defracted light beam makes with the normal

2. Which color of light is bent the most in a prism?

a. green

b. blue

c. red

d. violet

e. yellow

Answer 1

1. None of the above alternatives, although (a) comes closest.  The critical angle is the largest angle of incidence (the angle between the incident ray and the normal) at which total internal refection  (TIR) occurs. It is given by arcsin(n2/n1).  TIR can take place only when n2<n1.

2. In order of increasing bending: ROYGBV.  The nearest electronic energy levels lie in the UV in glass.  Hence the refractive index should increase as the wavelength gets shorter.