plz answer as soon as possible
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Persons near view is v = - 50 cm
least distance of distinct vision = -25 cm
By lens makers formula
1/f =1/-50 - ( 1/-25)
1/f = -1/50 + 1/25
1/f = -1/25 ( 1/2-1)
1/f = -1/25 ( 1-2/2)
1/f = -1/25 ( -1/2)
1/f = 1/25 × 1/2
f = 25 × 2
f = 50 cm
Power = 1/0.5 m = 10/5 = 2 D
To read near things to read book , newspaper , phone etc with 2 D lens
persons far point is 3 m
and focal length will be -3 m
Power of lens = 1/f
==> 1/-3
==> -0.33 D
To see star he needs the given converging lens of power -0.33 D.
"-" sign means : short sightedness
"+" sign means : long sightedness