A biconvex thick lens is constructed with glass (μ = 1.50). Each of the surfaces has a radius of 10 cm and the thickness at the middle is 5 cm. Locate the image of an object placed far away from the lens.

Biconvex lens with each surface has a radius (

Thickness of lens (t) = 5 cm

Refractive index of lens ==1.50

Position of object =

At first refraction occurs at A

By using lens equation:

⇒

⇒

⇒

Now, the second refraction occurs at B

Object distance =u= (30-5) = 25 cm (a virtual object)

Radius

So, (by using lens equation)

So, the image is formed 9.1 cm further from the 2^{nd} surface of the lens.

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