Question

To read a poster on a wall, person with defective visionneeds to stand at a distance of 0.4m from the poster.
A person with normal vision can read the poster from a distance of 2.0 m. Which one of the following lens may
be used correct the defective vision ?

Answer 1

Heya......!!!!

In this question we need to take out Focal Length first ,,,

GIVEN ;
=> u = 2m
=> v = 0.4 m
=> f = ?

By applying formulae , we get.....

1/v - 1/u = 1/f

=>> 1/f = ( -5+1 )÷2 = -4/2
=> 1/f = -2

=> So ,,power ( P ) = 1/f = 2D

The power of concave lens required ➡ 2 D .



Hope It Helps u ^_^