Question

A divergent lens of focal length 30cm forms the image of an object size 6 cm on the same side as the object at a distamdiof 15 cm from its optical centre . Use lens formula to determine the distance of the object and size of the image

Answer 1

Please find below the solution to the asked query:

Given that the focal length and object distance as,

f=-30 cm and v=-15 cm

and the size of the object is, ho=-6 cm.
From the len's formula,

1v-1u=1f ⇒ 1u = 1v-1f ⇒ u=fvf-v ⇒ u=-30-15-30+15⇒u=-30 cm

So, According to the magnification formula,

m = hihO = vu ⇒ hi =hO vu ⇒ hi = -15-30×6 ⇒ hi= 3 cm

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