Question

The person cannot see objects clearly beyond 50cm,The power of lens to correct the vision is .+5d .-0.5D .-2D .+2D GIVE REASON

Answer 1

-2D as P=1/f , first also 50 cm =1/2 m therefore P= 2D moreover concave lens are used so power is -

Answer 2

Answer:

The power of lens to correct the vision is +2D.

Explanation:

The person cannot see objects beyond 50 cm clearly, as given, power of lens correction will be calculated as follows –

Given is the focal length f = 50 cm

Power P = ?

From the formula of power of lens, we have -  

$\bold{P=\frac{1}{f}}$

$\begin{array}{l}{\Rightarrow f=50 \mathrm{cm}} \\ {\Rightarrow P=\frac{1}{50 \mathrm{cm}}}\end{array}$

$\begin{array}{l}{\Rightarrow P=\frac{1}{0.5 m}} \\ {\Rightarrow P=\frac{10}{5}} \\ {\Rightarrow P=\frac{1}{2}}\end{array}$

Therefore, P = 2D.