Question

How will u distinguish between a convex and concave lens without touching them

Answer 1

place those lens near objects
if object seems to be big then that is convex
if object seems small that is concave lens

Answer 2

We can differentiate between a convex and concave lens by seeing the image.

• On keeping the lens near a printed page, if letters appear magnified, the lens is convex and if the letters appear diminished, the lens is concave.
• On seeing a distant object through the lens, if its inverted image is seen, the lens is convex and if an upright image is seen, the lens is concave.