 # What is the difference between concave lens and convex lens

4 years ago
Dear Faheem

Convex lenses are thicker at the middle. Rays of light that pass through the lens are brought closer together (they converge). A convex lens is a converging lens.

When parallel rays of light pass through a convex lens, the refracted rays converge at the focal point. The image formed is magnified (you can use this lens as a magnifier, or a simple camera lens by itself). It’s also called “positive” lens.

Concave lenses are thinner at the middle. Rays of light that pass through the lens are spread out (they diverge). A concave lens is a diverging lens.

When parallel rays of light pass through a concave lens the refracted rays diverge so that they appear to come from one point called the principal focus. The image formed is diminished. It’s also called “negative” lens. This lens can’t be used to form an image by itself, but in combination(s) with positive (converging) lenses it is used to shorten the focal length.

This is just a basic, simple answer to your question. There are many types or shapes of concave / convex lenses (including their combinations) and I could easily go on for a week about optics.

Regards

3 years ago
a lens which has one or two spherical surfaces such that it is thicker in the middle and tapering at the edges is called convex lens.
a lens which has one or two spherical surfaces such that it is thicker at the edges and tapering in the middle is called concave lens.

3 years ago

Convex lenses are thicker at the middle. Rays of light that pass through the lens are brought closer together (they converge). A convex lens is a converging lens.

When parallel rays of light pass through a convex lens, the refracted rays converge at the focal point. The image formed is magnified (you can use this lens as a magnifier, or a simple camera lens by itself). It’s also called “positive” lens.

Concave lenses are thinner at the middle. Rays of light that pass through the lens are spread out (they diverge). A concave lens is a diverging lens.

When parallel rays of light pass through a concave lens the refracted rays diverge so that they appear to come from one point called the principal focus. The image formed is diminished. It’s also called “negative” lens. This lens can’t be used to form an image by itself, but in combination(s) with positive (converging) lenses it is used to shorten the focal length.

Principal Axis is the Radius of Curvature. And we also make ray diagrams.

3 years ago
Convex lens are thicker at the middle and converge parallel light rays to its focus.
Concave lens are thinner at the middle and diverge parallel light rays. It appears that the rays are coming from the focus.