<prompt> Diopteric power is related -Directly to square of focal lengthInversely to focal lengthDirectly to focal lengthInversely to square of focal length  <response>: Ans. is b i.e. Inversely to focal length Optical powero Optical power also referred to as dioptric power, refractive power, focusing power, or convergence power is the degree to which a lens, mirror, or other optical system converges or diverges light. It is equal to the reciprocal of the focal length of the device: P 1f. High optical power corresponds to short focal length. The SI unit for optical power is the inverse metre m 1, which is commonly called the dioptreo Converging lenses have positive optical power, while diverging lenses have negative power. When a lens is immersed in a refractive medium, its optical power and focal length change. 