A converging lens frorms an upright image that is four times the object size. Given that the focal length is 20cm determine object distance
To determine the object distance of the converging lens, we can use the lens formula:
1/f = 1/do + 1/di
where:
f = focal length of the lens
do = object distance (distance from the lens to the object)
di = image distance (distance from the lens to the image)
Given that the focal length is 20 cm and the image is four times the size of the object, we can say that di = 4do.
Substitute in the values:
1/20 = 1/do + 1/4do
Multiply through by 20do:
1 = 20 + 5
1 = 25
Therefore, the object distance (do) is 25 cm.