Answer to Question #92237 in Optics for Sridhar

Question

Four lenses a,b,c,d of power +100D , -50D
+20D and 5D . Which lenses will you use to design a compound microscope for best magnification
1) a&c
2)b&d
3)c&d
4a&b

Answer 1

The magnification of microscope M is given by formula

$$M=M_{objective} ×M_{eyepiece} (1)$$

The magnification of lens is equal to

$$M = d×D (2)$$

where d=0.25 m, D is power of lens

Only convex lenses are used in the microscope.

Using (1) and (2) we can say that the microscope will give the best magnification when the lenses give the largest power.

In our case, we have +100D and +20D

Answer:

1) a&c