Question 31
Refraction of LightA 45° triangular glass prism can be used as a reflector of light because
- A.refraction never takes place in such a prism
- B.the angle of reflection equals the angle of incidence
- C.the refractive index of glass is less than 1
- D.It is transparent
- E.the critical angle for glass is less than 45°.
Show the answer and explanation
Answer: E (the critical angle for glass is less than 45°.)
Explanation
Light meets the long face at 45°, which is more than the critical angle of glass (about 42°), so it is totally internally reflected.