A converging lens with a focal length of 20 cm 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?
To determine the distance at which the paper screen should be placed to produce a clear image, we can use the lens formula:
1/f = 1/u + 1/v
Where:
- f is the focal length of the lens
- u is the object distance (distance between the lens and the object)
- v is the image distance (distance between the lens and the image)
In this case, the sun can be considered an object located at infinity, so the object distance (u) is equal to infinity.
When the object is at infinity, the lens formula simplifies to:
1/f = 1/v
Substituting the given focal length (f = 20 cm) into the equation, we get:
1/20 = 1/v
Now, let's solve for v:
v = 20 cm
The image is formed 20 cm from the lens. Therefore, the paper screen should be placed 20 cm away from the lens to produce a clear image of the sun.