Question

What is a concave lens?

Answer 1

Answer: A concave lens is a type of lens that diverges a straight light beam coming from the source to a diminished, upright, virtual image is known as a concave lens. Concave lenses have at least one surface curved inside.

Answer 2

A concave lens is a lens that has at least one of its surfaces or both surfaces curved inwards. Due to this reason, this lens diverges the light that falls on it and hence is also called a diverging lens. The concave lens is thinner in the middle compared to its edges. These are used in flashlights, binoculars, telescopes, etc.
Please see attached image for reference.