Question

A light ray travels in the way from glass to the water. After passing through water, the ray grazes along the water air interface. The value of refractive index of glass in terms of i

Answer 1

a)yellow,orange, red

(b)violet, indigo,blue

(c)all colours

(d)all except green

A)  

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Since green light grazes the surface after refraction the incident angle must be critical angle for green light.

As wavelength increases from violet to Red, the refractive index μ decreases from Violet, to Red.

and Since θc=sin−11μ we have critical angle increases from Violet to Red.

Critical angle for yellow orange and red and greater than θg .

Therefore they will emerge out in air, the other colours will be totally internally reflected.

Hence a is the correct answer.