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Question
(a) A ray of monochromatic light enters glass PQRS as shown in the fig. Complete the path of ray till it emerges from the glass. (Critical angle of glass is 420).

(b) Draw diagram of a prism periscope.
(c) What are the advantages of total internal reflecting prism over plane mirror?
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Solution

Note : here that when the angle of incidence in the denser medium is more than the critical angle (= 42), then the ray undergoes total internal reflection.
At angle of incidence equal to critical angle, the ray grazes the interface.
(b) Diagram of prism periscope:

(c) In case of reflection from plane mirror, all of light in not reflected. In case of total reflecting prism, all rays failing beyond critical angle will be totally reflected. The intensity of reflected light is equal to the intensity of incident light in case of total internal ref;lection but not in case of reflection from plane mirror.
In addition, the reflection through a thick mirror causes multiple image formation as well as lateral inversion of image.
Due to the above two reasons, the total reflecting prisms are preferred over the plane mirrors.
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RELATED QUESTIONS
The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index`3/2`, placed in water of refractive index `4/3`.Will this ray suffer total internal reflection on striking the face AC? Justify your answer.

i) Observe the given figure and answer the following questions.
a) Identify and write the natural process shown in the figure.
b) List the phenomena which are observe in this process.
c) Redraw the diagram and show above phenomena in it.

Plot a graph between
Angle of incidence versus angle of reflection,
Complete the following diagram to show the path of the ray of a single colour in the diagram as if enters in and emerges out of the prism. Mark the angles wherever necessary. (Critical angle for glass = 42°).

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The entire light is reflected back into the denser medium is called ______.
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A ray of light passes through a prism of refractive index `sqrt2` as shown in the figure. Find:

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- The angle of minimum deviation for this prism.
Find the value of θ in the given figure.

