A lens has a focal length of -15 cm. What type of lens is it? (2020)

A lens has a focal length of -15 cm. What type of lens is it? (2020)

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: Identify the sign of the focal length. In this case, the focal length is -15 cm, which is negative.
Step 3: Know the types of lenses. A lens can be either convex (positive focal length) or concave (negative focal length).
Step 4: Since the focal length is negative, it indicates that the lens is a concave lens.

Focal Length – The focal length of a lens determines its type; a negative focal length indicates a concave lens, while a positive focal length indicates a convex lens.
Lens Types – Understanding the difference between concave and convex lenses is crucial for identifying lenses based on their focal lengths.