Q. A prism has a refracting angle of $60^{o}.$ When placed in the position of minimum deviation, it produces a deviation of $30^{o}.$ The angle of incidence is
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Solution:
In minimum deviation of prism angle of incidence $i$ becomes equal to the angle of emergence $e$ and the refracted ray becomes parallel to the base of the prism.
For prism, $i+e=\delta_{m}+A$ ; where $A$ is refracting angle of prism, since $i=e$ ,
So, $i=\frac{\delta_{m} + A}{2}=\frac{30 ^\circ + 60 ^\circ }{2}=45^\circ $ .
So, $i=\frac{\delta_{m} + A}{2}=\frac{30 ^\circ + 60 ^\circ }{2}=45^\circ $ .