State two applications each of a convex and concave lens.

The two applications of a convex lens are:-

1. It is used as an objective lens in a telescope, camera, slide projector, etc.
2. It is also used as a magnifying glass.

The two applications of a concave lens are:-

1. A person suffering from short-sightedness or myopia wears spectacles having concave lens.
2. A concave lens is used as eye lens in a Galilean telescope to obtain an erect final image of the object.