Question

A myopic person has a far point of 1.000m. If she wears her eyeglass 2.0cm in fromt of here eyes, what is the power of her eye glass?

Answer 1

Answer:

51 dioptre

Explanation:

u = Object distance =  2 cm

v = Image distance = 1 m

f = Focal length

Lens Equation

$\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\\\Rightarrow \frac{1}{f}=\frac{1}{0.02}+\frac{1}{1}\\\Rightarrow \frac{1}{f}=\frac{1.02}{0.02}\\\Rightarrow \frac{1}{f}=51\\\Rightarrow f=\frac{1}{51}$

Power of lens

$P=\frac{1}{f}\\\Rightarrow P=\frac{1}{\frac{1}{51}}\\\Rightarrow P=51\ D$

Power of the eye lens is 51 dioptre.