When the refracted light just grazes the boundary the incident angle is called a critical angle.
Using snell's law at face AC.
1.5sin60∘=n×sin90∘
⇒1.5×23=n=4x
⇒33=x
⇒x=27
JEE Main 2022 — Physics Optics
2022integermedium
In the given figure, the face AC of the equilateral prism is immersed in a liquid of refractive index n. For incident angle 60∘ at the side AC, the refracted light beam just grazes along face AC. The refractive index of the liquid n=4x. The value of x is _____ .
(Given refractive index of glass =1.5)
Official previous-year question
Held on 26 Jul 2022 · Verified 6 Jul 2026.
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