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When does spherical aberration occur in optics?

1. When light rays pass through the edges of a lens

2. When light refracts off the edges of a lens

3. When light rays separate at the edges of a lens

4. When the velocity of light is different at the edges of a lens

The correct answer is: When light rays pass through the edges of a lens

Spherical aberration occurs when light rays enter a spherical lens and are not focused to the same point. This phenomenon primarily manifests when light rays that pass through the edges of the lens come to a different focus compared to those that pass closer to the center. Due to the design of spherical lenses, rays that travel through the periphery often converge at a farther point than those passing through the lens’s center. This discrepancy in focus leads to a blurred image as not all light rays converge accurately on the image plane. The other options describe different optical phenomena that do not specifically result in spherical aberration. For instance, the refraction and velocity variations at the edges do not adequately capture the essence of how spherical aberration arises; rather, they reflect other aspects of lens behavior. Focusing on how light rays travel through the lens and their respective points of convergence is crucial to understanding why light rays passing through the edges specifically lead to spherical aberration.