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1)

 The image of an object, formed by a plano-convex lens at a distance of 8 m behind the lens, is real and is one -third the size of the object. The wavelength of light inside the lens is 2/3 times the wavelength in free space. The radius of the curved surface of the lens is 


A) 1 m

B) 2 m

C) 3m

D) 6m

Answer:

Option C

Explanation:

μ=λairλmedium=1(2/3)=32

 Further , |m|=13=|vu|

             |v|=|u|3

                 u=-24 m     (real object)

          v=+8 m (real image)

  Now,   1v1u=1f=(μ1)(1+R1)

         18+124=(321)(1R)

        R= 3m