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Question
A magnifying lens has a focal length of 100 mm. An object whose size is 16 mm is placed at some distance from the lens so that an image is formed at a distance of 25 cm in front of the lens.
What is the distance between the object and the lens?
Solution
Given, focal length (f) = 100 mm
Size of object (h) = 16 mm
Image distance (v) = 25 cm = 250 mm
Lens formula is given by:
`1/f=1/v-1/u`
`1/100=1/250-1/u`
`1/u=1/250-1/100`
`1/u=(2-5)/500`
`1/u=-3/500`
u=-166.67mm
u=-16.66cm
The object is at a distance of 16.66 cm and in front of the mirror. The image is at a distance of
25 cm and in front of the mirror. Therefore, the distance between the object and the image is 25 cm-16.66 cm = 7.14 cm.
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A magnifying lens has a focal length of 100 mm. An object whose size is 16 mm is placed at some distance from the lens so that an image is formed at a distance of 25 cm in front of the lens.
Where should the object be placed if the image is to form at infinity?
Assertion: The focal length of the mirror is /and the distance of the object from the focus is V then the magnification of the mirror will be `("f"/"f−u")`
Reason: Magnification = `"image distance"/ "object distance"` = `(-"v"/"u")`
