## Question

Diameter of a plano-convex lens is 6 cm and thickness at the centre is 3 mm. If the speed of light in the material of the lens is , the focal length of the lens is:

### Solution

30 cm

As the lens is plano-convex, i.e., *R*_{1} = *R* and *R*_{2} = ∞,

As speed of light in the medium of lens is

From figure,

#### SIMILAR QUESTIONS

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