AB and CD are two slabs. The medium between the slabs has refractive index 2. Find the minimum angle of incidence (in degrees) at Q so that the ray is totally reflected by both the slabs.
Let the minimum angle be αFor first surface to completely reflect, 2Sinα⩾√2Sin90 => sinα⩾1/√2 =>α⩾45∘
For second surface to completely reflect, 2Sinα⩾√3Sin90 => sinα⩾√3/2
=> 
So satisfies both condition
Answer. Minimum angle of incidence so as to totally reflect from both surface is α=60∘
A ray of light is incident at an angle of 45o on a square slab of a transparent material. What should be the refractive index of the material of the slab so that total internal reflection occurs at the vertical face AB.
A ray of light is incident at an angle of 45o on a square slab of a transparent material. What should be the refractive index of the material of the slab so that total internal reflection occurs at the vertical face AB.
(IIT-JEE 2005)
A parallel sides slab ABCD of refractive index 2 is sandwiched between two slabs of refractive indices √2 and √3 as shown in the figure. The minimum value of angle such that the ray PQ suffers total internal reflection at both the surfaces AB and CD
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