What isfocal power of a spherical mirror or a lens? What may be the reason for using `P = frac(1)(f)` as its expression ?

What is power of a lens?

What is the power of lens?

What are the two types of spherical mirror?

What is power? What is its unit?

If a spherical mirror breaks, what type of mirrors are the individual pieces?

What are the reasons for 'Malin' mishap in Pune district? What are its effects?

Use your brain power : What are the needs of cells?

If two power of a thick lense is P_(1) and that of a thin lens is P_(2) then

An object is placed at a distance u from a concave mirror and its real image is formed on the screen placed at distance v from the mirror. If f is the focal length of the mirror, then the graph between frac(1)(v) versus frac(1)(u) is (magnitude only)

The focal length of a convex lens is 20 cm.What is the power?