Question

Q)a convex lens forms a real image 4 times magnified at a distance of 60 cm from the lens.calculate the focal length & the power of lens??

Answer 1

Hello ,

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●Given that,

m = -4 (Real image)

v = 60cm

●For lenses,

m = v/u = -4

So ,u= -60/4 = -15cm

●Now using the lens formula,

1/f = 1/v -1/u

=1/60-(-1/15) = 1/60 + 1/15

=5/60 = 1/12

So focal length f = 12cm = 0.12m

==> Power, P = 1/f = 1/0.12 = 8.3D. (Ans.)

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HOPE IT HELPS U !!!

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# NIKKY