Question

An object is to be seen through a simple microscope of focal length 12 cm. Where should the object be placed so as to produce maximum angular magnification? The least distance for clear vision is 25 cm.

Answer 1

For the simple microscope, we have:
Focal length, f = 12 cm
Least distance of clear vision, d = 25 cm
For maximum angular magnification,
Image distance = Least distance of clear vision
v = d = − 25 cm

The lens formula is given by

`1/v -1/u =1/f`

`=> 1/u =1/v -1/f`

On substituting the values, we get:

`1/u =1/-25 - 1/12`

`1/u =-(25+12)/300 = -37/300`

`=> u = -300/37 =-8.1  text/"cm"`

So, to produce maximum angular magnification, the object should be placed 8.1 cm away from the lens.