Question

Why is P = 1 / f ? A derivation please

Answer 1

Answer:

power refers to the ability of the optical object to converge or diverge light.

Whereas focus is the point on the principle axos when the light Ray's after reflection or refraction passes.

Higher the power, more the light will be diverged and smaller will be the focal length and vice versa.

from this we can say, P=1/f

Answer 2

Answer:

p = 1/f

Explanation:

power is inversely proportional to focal length

power is inversely proportional to focal lengthi.e power ∝ focal length

so,. power = 1 / focal length