- The power of a lens (P) is related to its focal length (f) by the formula P = 1/f, where f is in meters and P is in Dioptres. - Given P = -1.25 D. - meters. - Converting to centimeters: -0.8 meters 100 cm/meter = -80 cm. - A negative focal length indicates a concave lens. Myopia (nearsightedness) is corrected using concave lenses to diverge light rays before they reach the eye's lens.
A myopic person has a power of -1.25 Dioptre. What is the focal length and nature of his lens ?
Asked in UPSC CDS 1 2016 · Topic: Optics (Thin and Thick Lenses, lens combinations)
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