A narrow beam of light is incident normally on a $30 ° - 60 ° - 90 °$ prism (near vertex A) whose one side is reflecting as shown in the figure. Refractive index of material of prism is $μ = 2.2$ . The total deviation of the beam when it comes out of the prism is $n \times 36 °$ . Find $n$ .

Question

Smart Achievers · Accepted Answer

(5)

Beam is incident normally on reflecting surface. So it will retrace the path.

$θ_{c} = \sin^{- 1} (\frac{1}{2.2}) \Rightarrow θ_{c} < 30 °$

$∴$ $Deviation = 180 ° = 5 \times 36 °$

Solution

Q.
A narrow beam of light is incident normally on a $30 ° - 60 ° - 90 °$ prism (near vertex A) whose one side is reflecting as shown in the figure. Refractive index of material of prism is $μ = 2.2$ . The total deviation of the beam when it comes out of the prism is $n \times 36 °$ . Find $n$ .

Ans.
(5)

Beam is incident normally on reflecting surface. So it will retrace the path.

$θ_{c} = \sin^{- 1} (\frac{1}{2.2}) \Rightarrow θ_{c} < 30 °$

$∴$ $Deviation = 180 ° = 5 \times 36 °$

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Solution

Q. A narrow beam of light is incident normally on a 30°–60°–90° prism (near vertex A) whose one side is reflecting as shown in the figure. Refractive index of material of prism is μ=2.2. The total deviation of the beam when it comes out of the prism is n×36°. Find n.

Ans. (5) Beam is incident normally on reflecting surface. So it will retrace the path. θc=sin-1(12.2)⇒θc<30° ∴ Deviation=180°=5×36°

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Ans.
(5)

Beam is incident normally on reflecting surface. So it will retrace the path.

$θ_{c} = \sin^{- 1} (\frac{1}{2.2}) \Rightarrow θ_{c} < 30 °$

$∴$ $Deviation = 180 ° = 5 \times 36 °$