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Question
An object is placed at a distance of 10 cm from a convex lens of focal length 12 cm, find out at what distance image will be formed from the lens and what is the nature of image.
Solution
Given: Focal length (f) = 12 cm,
Object distance (u) = −10 cm
To find: i. Image distance (v)
ii. Nature of image
Formula: `1/"f" = 1/"v" - 1/"u"`
Calculation: From formula,
`1/12 = 1/"v" - 1/(- 10)`
∴ `1/"v" = 1/12 - 1/10`
`= (10 - 12)/120`
`= (- 2)/120`
`= - 1/60`
∴ v = - 60 cm
A negative sign indicates an image is formed on the same side as that of the object.
The image is erect, virtual and magnified.
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