At closest distance of the object the image is formed at least distance of distinct vision and eye is most strained.

1

v

−

1

u

=

1

f

or

1

−25

−

1

u

=

1

5

-

1

u

=

1

5

+125 =

5+1

25

or u = -

25

6

cm = - 4.2 cm
At farthest distance of the object the image is formed at ∞ and eye is most relaxed.

1

v

−

1

u

=

1

f

or

1

−∞

−

1

u

=

1

5

u = – 5 cm
(b) Maximum angular magnification
mmax = [1+

D

fe

] or

D

umin

=

25

25 6

⇒ mmax = 6
Minimum angular magnification,
mmin =

D

fe

or

D

umax

=

25

5

= 5