# At what distance from the lens is the image

## Homework Statement

A punctual source of light is in the focal point of a diverging lens. in which distance from the lens is the image. Draw the road of rays.

## Homework Equations

The objects at focal point don't have an image.

## The Attempt at a Solution

http://s32.postimg.org/ociblmif9/image.png
So how should I draw the rays (it says in the problem)?

Merlin3189
Homework Helper
Gold Member
My feeling would be to find the position of the image, then draw the ray paths accordingly.

You can find the image position using a formula, or, perhaps more interestingly, by drawing rays for an off-axis point at the focal distance. (The problem with the focal point being on-axis is that all the standard rays are coincident.)

ehild
Homework Helper

## Homework Statement

A punctual source of light is in the focal point of a diverging lens. in which distance from the lens is the image. Draw the road of rays.

## Homework Equations

The objects at focal point don't have an image.
Are you sure? Where is the image if the object is very near to the focal point in case of a converging lens?
What do you know about the focal length of a diverging lens?
Where is the image if the object distance is do = |f|?