Answer to Question #108951 in Optics for Leticia

Question

Sketch a ray diagram for a spherical convex lens with an object at Do = 2f.

Answer 1

As per the given question,

Object position (u)=2f

Let the focal length of the spherical lens =f

let the final position of the image (v).

Now, we know that

$\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}$

Now, substituting the values in the above,

$\Rightarrow \dfrac{1}{v}-\dfrac{1}{-2f}=\dfrac{1}{f}$

$\Rightarrow \dfrac{1}{v}=\dfrac{1}{f}-\dfrac{1}{2f}=\dfrac{1}{2f}$

Hence, v=2f