A figure divided into squares, each of size `1.0 mm^2` is being viewed at a distance of 9.0 cm through a magnifying lens of focal length 10 cm held close to the eye.
(i) The magnification produced by the lens will be

Explanation

(a) The image formed will be virtual, erect and magnified.
The image will be formed behind the object.
(b) Area of each square of the object `="1 mm"^(2), u=-9cm, f=+10cm`
`"Using "(1)/(v)-(1)/(u)=(1)/(f)`
`(1)/(v)-(-(1)/(9))=(1)/(10)`
`rArr v=-90cm`
`"Magnification "=(v)/(u)=(-90)/(-9)=10`
`"Area of each square in the image "=(10)^(2)xx1=100mm^(2)=1cm^(2)`
(c ) `"Angular magnification M"=(D)/(u)=(25)/(9)=2.8`