Q23 of 38 Page 1

(i) Which property of concave mirror is utilized for using them as shaving mirrors?

(ii) Light passes through a rectangular glass slab and through a triangular glass prism. Using proper ray diagram, explain in what way does the direction of the two emergent beams differs with respect to the incident beam of light.


(iii) A concave lens has a focal length of 50 cm Calculate its power.

(i) It forms a virtual, erect and magnified image when object is placed between pole and focus of concave mirror. This property helps it to use as a shaving mirror.


(ii) In case of a rectangular glass slab emergent ray is parallel to incident ray but laterally displaced from the path of incident ray.



But in a prism it bends towards base of prism making an angle of deviation with the path of incident ray.



(iii)


Focal length = 50 cm or 0.5 m


P = 1/0.5


= 2 D


So, power = -2 D


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