The expected graphical representation of the variation of angle of deviation '$\delta$' with angle of incidence '$i$' in a prism is :

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Geometrical Optics

The expected graphical representation of the variation of angle of deviation '

δ

' with angle of incidence '

i

' in a prism is :

(A)(see structure)
(B)(see structure)
✓ Correct
(C)(see structure)
(D)(see structure)

Answer: (B)

Solution

For a prism,

δ = i + e - A

with

r_{1} + r_{2} = A

. As the angle of incidence is increased from a small value, the deviation first falls, passes through a single minimum at the symmetric passage

i = e

, and then rises again. The path is reversible, so every deviation above the minimum is produced by two different angles of incidence, one on each branch. The variation is therefore a curve that falls to one minimum and then rises, and neither a straight line nor a monotonic curve can represent it.

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Single correct option

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