Question

a convex lens forms a real image 4times magnified at a distance of 60cm from the lens calculate the focal length and power of lens

Answer 1

given :
magnification=m=-4[since it is real and magnified]
v= 60cm
object distance=u=?
magnification =m=V/u
u= 60/-4 =-15cm

Focal length=f=?
f=1/v - 1/u
=1/60 +1/15
=4+1/60
=5/60
f=60/5
=12cms

∴ Foal length of convex lens=12cm

Power=P=?
p=1/f (in m)
=100/f ( in cm)
=100/12
=+8.33 Diopters
∴ P=+8.3 D

Answer 2

Answer:

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