Question

The power of the lens of a myopic person is −3.75 D. Calculate the focal length of the lens.

Answer 1

Power −3.75 D indicates that lens is concave.

\[ \text{Applying, } \mathrm{P} = \frac{100}{f \text{(in cm)}} \]

\[\Rightarrow \ - \ 3.75 = \frac{100}{f \text{(in cm)}}\]

\[ \ f = -\frac{100}{3.75} \]

\[\therefore\ f = - \ 26.67 \ \text{cm}\]