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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Geometrical Optics

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Geometrical Optics

Determine the angle of minimum deviation for an equilateral prism...

Determine the angle of minimum deviation for an equilateral prism constructed from a material with a refractive index of 1.7321.732. What is the corresponding angle of incidence for this deviation?

Options

  1. A60^{}^{{}^{\circ}} and 60^{}^{{}^{\circ}}
  2. B60^{}^{{}^{\circ}} and 30^{}^{{}^{\circ}}
  3. C30^{}^{{}^{\circ}} and 60^{}^{{}^{\circ}}
  4. D45^{}^{{}^{\circ}} and 45^{}^{{}^{\circ}}

Correct answer

A. 60^{}^{{}^{\circ}} and 60^{}^{{}^{\circ}}

Step-by-step solution

For an equilateral prism, the angle of the prism is A = 60^{}^{{}^{\circ}}.

The refractive index of the material is given as μ=1.732=3\mu = 1.732 = \sqrt{3}.

The relation between the refractive index, angle of prism, and angle of minimum deviation δm\delta_m is:

μ=sin⁡(A+δm2)sin⁡(A2)\mu = \dfrac{\sin\left(\dfrac{A + \delta_m}{2}\right)}{\sin\left(\dfrac{A}{2}\right)}

Substituting the given values:

\sqrt{3} = \dfrac{\sin\left(\dfrac{60^{}^{{}^{\circ}} + \delta_m}{2}\right)}{\sin\left(\dfrac{60^{}^{{}^{\circ}}}{2}\right)}

\sqrt{3} = \dfrac{\sin\left(30^{}^{{}^{\circ}} + \dfrac{\delta_m}{2}\right)}{\sin(30^{}^{{}^{\circ}})}

\sqrt{3} = \dfrac{\sin\left(30^{}^{{}^{\circ}} + \dfrac{\delta_m}{2}\right)}{\dfrac{1}{2}}

\sin\left(30^{}^{{}^{\circ}} + \dfrac{\delta_m}{2}\right) = \dfrac{\sqrt{3}}{2}

Since \sin(60^{}^{{}^{\circ}}) = \dfrac{\sqrt{3}}{2}, we get:

30^{}^{{}^{\circ}} + \dfrac{\delta_m}{2} = 60^{}^{{}^{\circ}}

\dfrac{\delta_m}{2} = 30^{}^{{}^{\circ}} \Rightarrow \delta_m = 60^{}^{{}^{\circ}}

The corresponding angle of incidence ii at minimum deviation is given by:

i=A+δm2i = \dfrac{A + \delta_m}{2}

i = \dfrac{60^{}^{{}^{\circ}} + 60^{}^{{}^{\circ}}}{2} = 60^{}^{{}^{\circ}}

Thus, the angle of minimum deviation is 60^{}^{{}^{\circ}} and the angle of incidence is 60^{}^{{}^{\circ}}.
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