A converging lens with a focal length of 10cm is used to create an image of the sun on a paper screen. How far from the lens must the paper be placed to produce a clear image?
I don't know what variable I am trying to find. Am I trying to find do (distance of the object) or di (distance of the image)?
distance from the lens to the image.
The sun is infinitely far away for practical purposes so if you hold your paper at the focal point you will get the image. You will also burn a hole in the paper.
so the variable do = infinity?
Np,it asked for the image distance, the paper with the hole in it at the focal point.
something infinitely far away has its image right at the focal point.
Look at the diagrams in your book and think parallel rays coming from far away. Boy scouts light fires that way, or they did in the 1940s when I was a boy scout.
To determine the distance at which the paper screen should be placed to produce a clear image, we need to find the distance of the image (di).
In this case, the sun is considered a distant object, so we can assume that the object distance (do) is effectively at infinity. Therefore, we need to find di.
To find di, we can use the lens formula:
1/f = 1/do + 1/di
Where:
- f is the focal length of the lens (10 cm)
- do is the distance of the object (which we consider to be infinity)
By substituting these values into the lens formula, we get:
1/10 = 1/infinity + 1/di
Since the object distance is effectively at infinity, we can simplify the equation to:
1/10 = 0 + 1/di
If we solve for di, we get:
di = 10 cm
Therefore, the distance between the lens and the paper screen (distance of the image) should be 10 cm to produce a clear image of the sun.