The distance from the eye-lens to the retina is x . For a normal eye, the maximum focal length of the eye-lens is

Step-by-step solution

For a normal eye, the maximum focal length of the eye-lens corresponds to the fully relaxed state of the ciliary muscles, which occurs when viewing an object at infinity. Using the lens formula: 1 v - 1 u = 1 f Here, the object distance u = - and the image is formed on the retina, so the image distance v = x . Substituting these values into the lens formula: 1 x - 1 - = 1 f_ max 1 x - 0 = 1 f_ max f_ max = x Thus, the maximum focal length of the eye-lens is equal to x .