Question

When you are young, the minimum distance your eyes can focus is 20cm. As you get older, your eyes start to focus on objects only at 60cm. What is the focal length of the lens you need to use to be able to see the objects at 20cm? You can assume the distance between the eye lens and the retina to be 2cm.

Answer 1

solution If the image of an object at 20cm from the eye lens is formed by the lens at 60cm from the eye then we can see the object placed at 20 cm. That is O = object distance = -20cm i = image distance = -60cm from Ź - = = = = -20 = ť OR - 0 + ² = 1 =7673_=1 a že = $ or to 30 cm 30 cm