The Total solution for NCERT class 6-12
Double-convexlenses are to be manufactured from a glass of refractive index 1.55, with bothfaces of the same radius of curvature. What is the radius of curvature requiredif the focal length is to be 20 cm?
Refractive index of glass,
Focal length of the double-convex lens, f =20 cm
Radius of curvature of one face of the lens= R1
Radius of curvature of the other face of thelens = R2
The value of R can becalculated as:
Hence,the radius of curvature of the double-convex lens is 22 cm.