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Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsTIR/Prism and DispersionMedium2 minPYQ_2023
PhysicsMediummultiple choice

A plane polarized blue light ray is incident on a prism such that there is no reflection from the surface of the prism. The angle of deviation of the emergent ray is δ=60o (see Figure-1). The angle of minimum deviation for red light from the same prism is δmin=30o (see Figure-2). The refractive index of the prism material for blue light is 3. Which of the following statement(s) is(are) correct?

Question diagram: A plane polarized blue light ray is incident on a prism such

Options:(select one or more)

Answer:
A, C, D
Solution:

For no reflection:

tani=3

i=60°

Applying Snell's law at left interface, we get

1×sini=3×sinr1sinr1=12r1=30o

Now, for given values

δ=i+e-A60°=60°+e-Ae=A

Then, 

A=r1+r2r2=A-r1=30o

For red light:

Expression to find minimum deviation is given by,

μ=sinA+δm2sinA2=sin60°+30°2sin60°2=1212=2

Stream:JEE_ADVSubject:PhysicsTopic:Geometrical OpticsSubtopic:TIR/Prism and Dispersion
2mℹ️ Source: PYQ_2023

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