What is the primary function of a concave lens?

A concave lens is specifically designed to diverge light rays that are passing through it. When parallel rays of light enter a concave lens, the lens bends these rays outward, effectively causing them to spread apart. This divergence creates a virtual image that appears to be located on the same side of the lens as the object being viewed, thus making the object appear smaller or further away.

Concave lenses are commonly used in eyeglasses for individuals who are nearsighted, as they help in correcting the focal point by allowing light rays to diverge appropriately before reaching the eye. This adjustment helps the wearer to clearly see distant objects, which are typically blurred due to the light focus being in front of the retina rather than directly upon it.

In contrast, a concave lens does not filter light, converge light, or primarily magnify images. While it can affect image size, its fundamental characteristic is to cause light to diverge. This is the critical distinction that defines the primary function of a concave lens.