Lens Maker's Formula MCQ - Practice Questions with Answers

Lens Maker's formula -

Derivation of Lens maker formula - 

Let us take a lens having refractive index = n₂ and the surrounding is having refractive index = n₁. Also let us assume that the lens is having two refracting surface having radii R₁ and R₂. 

As we have learned the formula of refraction at a single spherical surface. Let us apply this on the surface (1), we get - 

Similarly for the second surface - 

Here, v₁ is the position of image formed by the first surface and the same image will now act as object for the second surface.

Now adding equation (1) and (2),

Now we are going to arrange this equation in the desired for as -

we get,

                                                         Where, 

There are ceratin limitations of this lens maker’s formula - 

• The lens should not be thick so that the space between the two refracting surfaces can be small.
• The medium used on both sides of the lens should always be same.