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anony12 · Jun 2, 2009, 01:57 AM

I really need help with this particular question as I am having trouble.

Q. If a beam of unpolarised light, travelling inside a block of glass of refractive index 1.5 undergoes total internal reflection at one of the internal surfaces, then:

A The beam must be incident on the surface at the critical angle.
B There is no reflected beam.
C The reflected beam is completely polarised.
D The refractive index outside the block must be less than 1.5.
E The refractive index outside the block must be greater than 1.5.

Thank you

Perito · Jun 2, 2009, 04:35 AM

Q. If a beam of unpolarised light, travelling inside a block of glass of refractive index 1.5 undergoes total internal reflection at one of the internal surfaces, then:

A The beam must be incident on the surface at the critical angle.
B There is no reflected beam.
C The reflected beam is completely polarised.
D The refractive index outside the block must be less than 1.5.
E The refractive index outside the block must be greater than 1.5.

A. Exactly the critical angle? What if it's a bit greater or less. Will there still be reflection?
B. If it "undergoes total internal reflection", this can't be true.
C. What's going to polarize it?
D and E - For reflection, the refractive index of the material outside the block must greater than, less than, or equal to the refractive index of the block of glass. The block of glass has a refractive index of 1.5.

Glenbrook: Total Internal Reflection

Hyperphysics: Total Internal Reflection

Wikipedia: Total Internal Reflection