A lens is a transparent optical device with curved surfaces that refract light, causing it to converge or diverge. Lenses are commonly used in optics to focus or diverge light rays and have various applications in imaging, vision correction, and scientific instruments. The two most common types of lenses are convex lenses and concave lenses.
Convex Lens:
A convex lens is thicker at the center than at the edges. It converges light rays that are parallel to its principal axis (the line passing through the center of the lens) to a focal point on the opposite side of the lens. Convex lenses are commonly used in magnifying glasses, eyeglasses for farsightedness (hyperopia), and camera lenses.
Concave Lens:
A concave lens is thinner at the center than at the edges. It causes parallel light rays to diverge, and if extended backward, they appear to converge at a virtual focal point. Concave lenses are used in correcting nearsightedness (myopia) in eyeglasses and are also part of optical systems in scientific instruments.
The properties of lenses are determined by their focal length, which is the distance from the lens to the focal point. The focal length can be positive (for converging lenses) or negative (for diverging lenses).
Lenses are crucial components in optical systems, including cameras, microscopes, telescopes, and eyeglasses. They play a key role in manipulating light to form images or correct vision. The study of lenses and their behavior falls under the branch of physics known as optics.