Question

name the type of lens and find the focal length of lens if the power of lens is +2.5​

Answer 1

Answer:

Here f = 40cm which is positive, it means the lens is a convex lens. Magnification m = -v/u = 3. It means v = -3u. It means the object is placed 20cms in front of the mirror.

Answer 2

Answer:

The focal length of a lens = 1/power of the lens

Therefore the focal length of the lens = 0.4m

The lenses with +ve power are generally convex lenses.