draw the ray diagram of compound microscope for the image formation at the distance of least distinction
Answers
where, AB = object, A'B' = image formed by objective and A''B'' = image formed by eyepiece
f
o
= focal length of objective,
u
o
= object distance from objective
v
o
= image distance from objective
D = distance of least distinct vision
l = length of the microscope
(b). For the least distance of clear vision, the total magnification is given by:
m=−Lf
o
(1+Df
e
)=m
o
.m
e
...(1)n2
where, L is the separation between the eyepiece and the objective
f
o
is the focal length of the objective
f
e
is the focal length of the eyepiece
D is the least distance for clear vision
Also, the given magnification for the eyepiece:
m
e
=5=(1+Df
e
)
5=1+20/f
e
⇒f
e
=5cm
u
e
1
=−
20
1
−
5
1
=−
4
1
u
e
=−4
L=v
o
+∣u
e
∣
14=v
o
+u
⇒v
o
=10
⇒u
o
=
−4
v
o
=−2.5
Hencef
0
=−
5
uv
o
=
5
4×2.5
=2cm