Question 14 :

The lens-makers' equation can be written as 1 _ (n2 _ 1x 1 _ 1 ) f n1 R1 R2 where in2 represents the index of refraction of the lens material and n1 is that of the medium surrounding the lens. (a) A certain lens has focal length 43.4 cm In the air and index of refraction 1.55. Find its focal length in water. (Give your answer in cm.) :cm (b) A certain mirror has focal length 43.4 cm in the air. nd its focal length in water. (Give your answer in cm.)