Question

(i) If f = 0.5 m for a glass lens; what is the power of the lens ?(ii) The radii of curvature of this faces of a double convex lens are 10cm and 15cm. Its focal length is 12 cm. What is the refractive index of glass ?(iii) A convex lens have 20 cm focal length in air. What is focal length in water P (Refractive index of air water = 1.33 refractive index for air glass = 1.5)

Answer 1

p=1/f
p=10/5=2
f should be in meter

Answer 2

solution:P= 1
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f(-in meter)
P=1/0.5
P= 2