(a) For magnification by the magnifying lens.
Let us use lens formula
u = – 9 cm, f = + 10 cm

1

v

−

1

u

=

1

f

or

1

v

−

1

−9

=

1

10

1

v

=

1

10

−

1

9

= -

1

90

Image position v = – 90 cm
Magnification m =

I

O

=

v

u

or m =

−90

−9

= 10
For area 1 mm2, consider the height of object 1 mm, so height of image.

I

O

=

v

u

,

I

1mm

= 10 or I = 10 mm
Area of image A = 10 × 10 mm2 = 100 mm2 = 1 cm2
(b) Angular magnification, m =

D

u

=

25

9

= 2.78
(c) No, the linear magnification by a lens and magnifying power (angular magnification) of magnifying glass have different values
The linear magnification is calculated using m =

v

u

, whereas angular magnification is m =

D

u

=

β

α

, the ratio of angle subtended by image of object at eye lens ‘β’ to the angle subtended by object assumed to be at least distance at eye lens ‘α’.
The linear magnification and angular magnification in microscope have similar magnitude when image is at least distance of distinct vision i.e., 25 cm