Lenses
A lens is a piece of transparent material, such as glass or plastic, that is used to refract (bend) light. Lenses are used in eyeglasses, cameras, microscopes, telescopes, and many other optical instruments. There are two main types of lenses: convex lenses and concave lenses.
Convex Lenses
A convex lens is thicker in the middle and thinner at the edges. When light passes through a convex lens, it converges (comes together) at a point on the other side of the lens. This point is called the focal point. Convex lenses are also known as converging lenses because they cause light rays to converge.
Convex lenses are used in magnifying glasses, cameras, and telescopes to focus light and create enlarged images. The distance between the lens and the focal point is called the focal length.
Concave Lenses
A concave lens is thinner in the middle and thicker at the edges. When light passes through a concave lens, it diverges (spreads out) as if it came from a point on the same side of the lens. This virtual point is also called the focal point. Concave lenses are also known as diverging lenses because they cause light rays to diverge.
Concave lenses are used in devices such as eyeglasses and some types of cameras to correct vision problems and reduce the size of images.
Study Guide
- What are the two main types of lenses?
- Describe the shape of a convex lens and how it affects light.
- Explain the focal point of a convex lens.
- Give examples of devices that use convex lenses.
- Describe the shape of a concave lens and how it affects light.
- Explain the focal point of a concave lens.
- Give examples of devices that use concave lenses.
