A converging lens of focal length 5cm is used as a magnifying glass by a man whose nearpoint is 35cm. Calculate the magnification given by the lens

aydultimate

3 years ago

A is the right option
A magnifying glass is also known as a simple microscope and it usually produce errect and magnified image in front of the convex lens used. The image is always located at 25cm for a person with normal vision while the value will be different for a person with eyes defect.
In the question, the user has a long sightedness, he is having problem with his near point. It means instead of the image to be formed at 25cm, it was formed at 35cm due to his eyes defect
So V=35, f=5, m=?
1/f= 1/u - 1/v
Why do I use negative sign? I used negative sign because the image produced by a magnifying glass is virtual, erect and magnified
1/f = 1/u - 1/v
Divide through by v
v/f = m - 1, Note that m = v/u
35/5 = m - 1
7 = m - 1
m = 8