Question

a person needs a lens of power -0.5dioptre for correcting his distant vision.for correcting his near vision he needs a lens of power +1.5 dioptre.What is the focal lenght of the lens required for correcting his
1)distant vision
2)near vision

Answer 1

1)for distant vision;

Given,
power of lens = -0.5D

we have to find;
focal length

$f = 1 \div p$
$= 1 \div - 0.5$
$= - 10 \div 5$
$= - 2m$
$- 2 \times 100cm$
$- 200cm$
therefore, for correcting distant vision the person use concave lens 200cm .

2) for near vision;

Given;
power of lens = +1.5D
we have to find;
focal length;
$f = 1 \div p$
$= 1 \div 1.5$
$= 10 \div 15$
$= 2 \div 3m$
$= 200 \div 3cm$
$= 66.67cm$
therefore; for correcting near vision the person use convex lens 66. 67cm .


Hope you understand my answer. :-)
THANK YOU ❤❤

Answer 2

Answer:

1)for distant vision;

Given,

power of lens = -0.5D

we have to find;

focal length

therefore, for correcting distant vision the person use concave lens 200cm .

2) for near vision;

Given;

power of lens = +1.5D

we have to find;

focal length;

therefore; for correcting near vision the person use convex lens 66. 67cm .

Hope you understand my answer. :-)

THANK YOU ❤❤

Explanation: