Here's why:
* Refraction: Lenses work by the principle of refraction. This means that light bends as it passes from one medium (air) to another (the lens material, typically glass or plastic). The angle at which the light bends depends on the shape of the lens and the material it's made of.
* Focusing: By carefully shaping the lens, you can control how the light bends, making it converge or diverge. This allows the lens to focus light onto a specific point, creating an image.
* Speed remains constant: While the direction of light changes, the speed of light remains constant. This is because the speed of light is determined by the medium it travels through, and the medium doesn't change when the light passes through a lens.
Types of lenses:
* Convex lenses: These lenses are thicker in the middle than at the edges. They converge light rays, focusing them to a point. This is why they are used in magnifying glasses and cameras.
* Concave lenses: These lenses are thinner in the middle than at the edges. They diverge light rays, spreading them out. This is why they are used in telescopes and eyeglasses for nearsightedness.
