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Refraction: Reflection after passing the critical angle

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Dec11-12, 06:28 PM
P: 106
If the angle of incidence is greater than the critical angle then it is reflected back in to same medium. Is this reflection normal reflection? (as in it obeys all the rules of reflection, like reflection in mirrors) Or is it a bit different?
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Dec11-12, 06:37 PM
P: 106
And also, in my book, under total reflection prisms, they've given the advantages of total reflection prisms as-

The reflection efficiency is nearly 100% as against an ordinary plane mirror whose reflectivity is poor.

There is is no problem of multiple reflections in the case of prisms while this problem spoils the quality of images in mirrors.

How can a plane mirror have poor reflectivity? What happens to the light that is not reflected? I thought mirrors reflected all the light.

And what do they mean by multiple reflection?
Dec11-12, 06:41 PM
Sci Advisor
P: 2,470
Total internal reflection follows normal reflection rules.

Mirror absorbs a portion of the light. It also reflects both at the front glass surface and the back surface, that's the multiple-reflection problem the book mentions. Light reflected from the back surface might be reflected back into the mirror again by the front surface, and so on. This will contribute to the absorption losses as well.

Dec11-12, 07:04 PM
P: 106
Refraction: Reflection after passing the critical angle

By front surface you mean the surface of the glass and by back portion you mean the silver reflecting surface on the back right? Oh and what are co axial rays? (Sorry for adding questions every post)

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