QBManager

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

365123 The refractive index of the material of a prism is $\sqrt{2}$ and the angle of the prism is 30°. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is

1 30°

2 zero

3 45°

4 60°

Explanation:

supporting img
Given that $μ = \sqrt{2},$ $A = 30^{0}$
Angle of incidence $= i, r_{2} = 0^{0}$
$μ = \frac{\sin i}{\sin r_{1}}$ & $A = r_{1} + r_{2}$
$∴ \sin i = μ \sin 30^{0} = \sqrt{2} \frac{1}{2} = \frac{1}{\sqrt{2}} = \sin 45^{0}$
$∴ i = 45^{0}$

NEET - 2018

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

365124 The cross-section of a prism has the form of an isosceles triangle. One of the equal faces is silvered. A ray is normally incident on the other once's face and being reflected twice inside the prism emerges through the base of prism perpendicular to base. Angle of prism is found to be $π / n .$ The value of $n$ is
supporting img

1 3

2 7

3 5

4 9

Explanation:

Let angle of prism is $α$ and other two angles are $β$ each. As $N N^{'}$ is parallel to $P Q$ .
$∠ P Q R = ∠ Q R N^{'}$ (Complimentary angles)
$\Rightarrow 2 α = β$
supporting img
Now from $△ A B C α + 2 β = 180^{\circ}$
$α + 2 (2 α) = 180^{\circ}$
$5 α = 180^{\circ}$
$α = 36^{\circ} = \frac{π}{5}$

Join With Us for More Updates

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

1 30°

2 zero

3 45°

4 60°

Explanation:

NEET - 2018

PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

1 3

2 7

3 5

4 9

Explanation:

For More Updates join with Us