How do lenses use refraction to focus light?

Lenses use refraction to bend and focus light rays.

Simple Explanation:

• A lens is a transparent object (like glass or plastic) with a curved surface.
• When light enters or leaves the lens, it changes direction because of refraction — light bends when it passes between air and the lens material.
• The shape of the lens decides how the light bends.

Two Main Types of Lenses:

1. Convex lens (thicker in the middle):
   • Bends light rays inward.
   • Focuses them to a point called the focus.
   • Used in magnifying glasses, cameras, eyes, and microscopes.
2. Concave lens (thinner in the middle):
   • Bends light rays outward.
   • Makes rays spread out, but they appear to come from a single point.
   • Used in eyeglasses for nearsightedness.

Key Point:

Lenses refract light to control its path, either focusing it to a point (convex) or spreading it out (concave). This is how they form clear images in optical devices.