A convexo-convex lens has focal length of f=10 cm.One of lens surfaces having radius of curvature of R=10 cm is coated with silver.Find position of image if object is at distance of 15 cm from lens.Refractive index of lens=1.5.(Ans.-2.14 cm)Please explain.

rohit rathi Grade: 12

        A convexo-convex lens has focal length of f=10 cm.One of lens surfaces having radius of curvature of R=10 cm is coated with silver.Find position of image if object is at distance of 15 cm from lens.Refractive index of lens=1.5.(Ans.-2.14 cm)Please explain.

7 years ago

Answers : (1)

SAGAR SINGH - IIT DELHI

879 Points

Dear student,

We have the Lens Formula as:

1/f = 1/v – 1/u
where f= focal length
v = image distance
u = object distance

There is a relation between radius of curvature and focal length given by the Lens Maker’s Formula.

1/f = (₁μ₂ – 1) (1/ R₁ – 1/R₂)
where f = focal length
1μ₂ = μ₂/ μ₁ = refractive index of the second medium / refractive index of the first medium
R₁ = radius of curvature of the first refracting surface of the lens
R₂ = radius of curvature of the second refracting surface of the lens.

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Sagar Singh

B.Tech, IIT Delhi