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.

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.

Please feel free to ask your queries here. We are all IITians and here to help you in your IIT JEE preparation.

All the best.

Win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.

Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar  respectively : Click here to download the toolbar..

Askiitians Expert

Sagar Singh

B.Tech, IIT Delhi