Derive the relation, μ = sin A + δ m 2 sin A 2 (symbols have their usual meanings) and show that i = A + δ m 2 , r = A 2 , for minimum angle fo deviation.

In the given diagram, O P is the incidence ray, which is making the angle i 1 with normal, and Q R is the angle of emergence, which is represented by i 2 . A is the prism angle and μ is the refractive index of the prism. Now, we know that, A = Prism angle, δ = Angle of deviation, i 1 = Angle of incidence, i 2 = Angle of emergent. In the case of minimum deviation, ∠ r 1 = ∠ r 2 = ∠ r A = ∠ r 1 + ∠ r 2 So, A = ∠ r = ∠ r = ∠ 2 r ∠ r = A 2 Now, again A + δ = i 1 + i 2 ( ∵ In the case of minimum deviation i 1 = i 2 = i and δ = δ m ) So, A + δ m = i + i = 2 i Now, i = A + δ m 2 Now, from snell's rule: μ = sin i sin r μ = sin A + δ m 2 sin A 2

E M B I B E

ISC Physics Class 12, Part-2>Chapter 4 - Refraction and Dispersion of Light through a Prism>QUESTIONS>Q 2

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IMPORTANT

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What is minimum angle of deviation? Draw graph between angle of incidence and deviation produced in the path of incident ray passing through a prism. Why $(i - δ)$ curve has two arms?

Important Questions on Refraction and Dispersion of Light through a Prism

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12th ICSE

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ISC Physics Class 12, Part-2>Chapter 4 - Refraction and Dispersion of Light through a Prism>QUESTIONS>Q 3

Derive the relation, $μ = \frac{\sin (\frac{A + δ_{m}}{2})}{(\sin \frac{A}{2})}$ (symbols have their usual meanings) and show that $i = \frac{A + δ_{m}}{2}, r = \frac{A}{2}$ , for minimum angle fo deviation.

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ISC Physics Class 12, Part-2>Chapter 4 - Refraction and Dispersion of Light through a Prism>QUESTIONS>Q 4

What do you understand by the term scattering of light? Why sky appears blue and dangerous signals are of red colour? Write Rayleigh's concept of scattering and relate it to above mentioned colours.

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ISC Physics Class 12, Part-2>Chapter 4 - Refraction and Dispersion of Light through a Prism>QUESTIONS>Q 5

Define angular dispersion and dispersive power of an optical medium. Explain why deviation is maximum for violet colour and minimum for red colour also explain the dependence of deviation on the refractive index.

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12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 4 - Refraction and Dispersion of Light through a Prism>QUESTIONS>Q 1

A ray of light is incident on a