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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.
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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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