A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?

Question

Philoid · Accepted Answer

We know the lens maker’s formula,

₂ and ₁ are refractive indices of lens and air. As we know the second one is a plane surface, hence, .

Now, if the lens is facing the object,

And, if it is the opposite then,

So, there are two cases, in the first one, focal length is positive and in the second case it is negative.