Question

a person needs a lens of power -4.5 D for the correction of equation what is the focal length of corrective lens and its nature

Answer 1

Answer:

Power = -4.5 D

so, according to the power formula,

P = 1/f (i)

⇒ f = 1/P ( from i)

So, substituting given power into the equation,

f = 1/-4.5

⇒ f = -0.22/0.23 m ( approx. value)

since focal length is negative, the corrective lens would be a concave lens. concave lens are diverging lens, i.e, meaning that it spreads out light rays that have been refracted through it.