Question

An eye specialist prescribes spectacles having focal length 25 cm for myopic eye, then the power of lens is

Answer 1

$\huge{\underline{\tt{\red{Answer-}}}}$

Focal length (f) = 25cm = -0.25m

Power(D) =?

$\boxed{D = \dfrac{1}{f}}$

$D= \dfrac{1}{-0.25}= -4D$

Power= -4D

Answer 2

Answer: P = 1/f = 1/-0.25 (covert cm in m)

=100/25 = -4D ( because myopic eye requires concave lens whose focal length is negative

Explanation: