Question

If one face of a prism of prism angle 30o and  is silvered, the incident ray retraces its initial path. The angle of incidence is:

Solution

Correct option is

45o

 

It is clear from the figure that the ray will retrace the path when the refracted ray QR is incident normally on the polished surface AC. Thus angle of refraction r = 30o.

We know that μ = sin i/sin r

  

                            

                             

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SIMILAR QUESTIONS

Q1

A convex lens of focal length 20 cm is cut into two equal parts so as to obtain two plano-convex lenses as shown in figure. The two parts are then put in contact as shown in figure. What is the focal length of the combination?

                                                                       

Q2

As shown in figure, a convergent lens is placed inside a cell filled with liquid. The lens has focal length +20cm when in air, and its material has refractive index 1.50. If the liquid has refractive index 1.60, the focal length of the system is: 

                                                                                     

Q3

A plano-convex lens of f = 20 cm is silvered at plane surface. Now, f will be (μ = 1.5): 

Q4

The plane face of a plano-convex lens is silvered. If μ be the refractive index and R, the radius of curvature of curved surface, then the system will behave like a concave mirror of radius of curvature:

Q5

A convex lens of focal length f is placed somewhere in between an object and a screen. The distance between the object and the screen is x. If the numerical value of the magnification produced by the lens is m, the focal length of the lens is:  

Q6

A ray of light suffers minimum deviation when incident on a 60o prism of refractive index  The angle of incidence is:

Q7

A ray is incident at an angle of incidence i on one face of a prism of small angle A and emerges normally from the opposite surface.  If the refractive index of the material of the prism is μ, the angle of incidence i is nearly equal to: 

Q8

The refracting angle of a prism is A and the refractive index of the prism is cot (A/2). The angle of minimum deviation is:  

Q9

A ray of light passes through an equilateral prism of glass in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to (3/4) of the angle of prism. The angle of deviation is: 

Q10

Angle of a prism is A and its one surface is silvered. Light rays falling at an angle of incidence of 2A on first surface return back through the same path after suffering reflection at the second silvered surface. Refractive index of the material is: