Question

at what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 36 cm from it

Answer 1

Answer:

focal length, f= 18 cm.

image distance, v= 36 cm. by the lens formula,

1/f = 1/v - 1/u

1/18 = 1/36 - 1/u

1/u = 1/-18 - 1/36

1/u = 2+1/36

1/u = 3/36

u = 9 cm.

object should be placed at a distance of 9 cm.

Explanation:

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