Question

A convex lens of focal length 15cm forms an image 10 cm from the lens?.how
far is the object placed from the lens ? Draw the ray diagram.
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Answer 1

Answer:

Focal length (f ) = -15 cm

Distance of image (v) = -10 cm

1v–1u=1f

1/u = -(1/10) – (1/- 15)

1/u =1/15 – 1/10

1/u = -0.033

u = -30 cm

so the object is placed 30 cm away from the concave lens