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प्रश्न
उत्तर
Magnification, m = `"I"/"O" = "u"/"v" = 2` (given)
⇒ v = 2 u
u + v = 45 cm (given)
u + 2u = 45cm
3u = 45cm
`therefore` u = 15 cm
Distance of lens from the object is 15 cm.
⇒ v = 2u = 30cm
We know, `1/"f" = 1/"u" + 1/"v"`
= `1/15 + 1/30 = 3/10 = 1/10`
⇒ f = 10 cm
Focal length is 10 cm.
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