A card sheet divided into squares each of size `"1 mm"^(2)` is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm) held close to the eye.
a) What is the magnification in produced by the lens? How much is the area of each square in the virtual image ?

Explanation

a) Here, area of each (object)
square `="1 mm"^(2),`
`u=-9cm, f=10cm`
As `(1)/(upsilon)-(-1)/(upsilon)=(-1)/(f)`
`(1)/(upsilon)=(1)/(f)+(1)/(u)=(1)/(10)(-1)/(9)=(-1)/(90)`
`v=-90cm`
Magnification, `m=(upsilon)/(|u|)=(90)/(9)=10`
`therefore` Area of each square in virtual image `=(10)^(2)xx1="100 sq. mm"`