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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.
Solution
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.
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