[" A convex lens has "20cm" focal "],[" length in air.What is the focal "],[" length in water? "],[48.2cm],[58.2cm],[68.2cm],[78.2cm]

A convex lens is of focal length 10 cm. What is its power?

(i) If f = + 0.5 m , what is the power of the lens ? (ii) The radii of curvature of the faces of a double convex lens are 9 cm and 15 cm . Its focal length is 12 cm . What is the refractive index of glass ? (iii) A convex lens has 20 cm focal length in air. What is the focal length in water ? (Refractive index of air-water = 1.33 , refractive index of air-glass = 1.5 ).

A plano convex lens has focal length f = 20 cm . If its plane surface is silvered, then new focal length will be

The power of a convex lens of focal length 25 cm is …………… .

" I length of convex lens in air is "10cm" .Its focal length in water is (refractive index of glass "=3/2" ,refractive index of water "