What happens to the image distance in the eye when we increase the distance of an object from the eye?
When the distance of an object from the eye is increased, the image distance remains constant. This is because the image is always formed on the retina, and the distance between the eye lens and the retina is fixed.
The eye adjusts its focal length through the process of accommodation to maintain clear vision. When viewing distant objects, the ciliary muscles relax, the lens becomes thinner, and its focal length increases. When viewing nearby objects, the ciliary muscles contract, the lens becomes thicker, and its focal length decreases. This adjustment ensures that the image is always focused clearly on the retina regardless of the object distance.
Explanation
The question tests the understanding that in the human eye, the image distance is essentially fixed because the retina is at a constant position from the lens. The textbook context explains accommodation: for distant objects, the ciliary muscles relax, making the lens thinner with increased focal length; for nearby objects, muscles contract, making the lens thicker with decreased focal length. Thus, when object distance increases, the eye adjusts its focal length (not image distance) to keep the image focused on the retina.
Solution Steps
Step 1: Identify that the image in the eye is formed on the retina, which is at a fixed distance from the eye lens.
Step 2: Conclude that the image distance remains constant since the retina position is fixed.
Step 3: Explain that the eye adjusts its focal length through accommodation to focus images clearly on the retina for objects at different distances.