If the focal length of a lens is -10 cm, what type of lens is it?

If the focal length of a lens is -10 cm, what type of lens is it?

Step 1: Understand what focal length means. Focal length is the distance from the lens to the point where light rays converge or appear to diverge.
Step 2: Know that focal length can be positive or negative. A positive focal length indicates a converging lens (like a convex lens), while a negative focal length indicates a diverging lens.
Step 3: Identify the given focal length. In this case, the focal length is -10 cm, which is negative.
Step 4: Conclude that since the focal length is negative, the lens must be a concave lens.

Focal Length – The distance from the lens to the focal point; negative values indicate a concave lens.
Lens Types – Concave lenses diverge light rays, while convex lenses converge them.