Question

A 3 cm tall object is placed perpendicular to the principal axis of a convex lens a focal length 30 cm. the distance of the object from the lens is 20 cm. use lens formula to find the position, size and nature of the image formed. [v=-60, h’=9]

Answer 1

Given :

• Object Height (Ho) = 3 cm

• Object Position (u) = - 20 cm

• Focal length (f) = 30 cm

• Convex Lens

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To Find :

• Image Position , size and nature

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Solution :

Use lens formula

⇒1/f = 1/v - 1/u

⇒ 1/v = 1/f + 1/u

⇒ 1/v = 1/(30) + 1/(-20)

⇒ 1/v = 1/30 - 1/20

⇒ 1/v = (2 - 3)/60

⇒ 1/v = -1/60

⇒ v = - 60 cm

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⇒m = v/u = H'/Ho

⇒-60/-20 = H'/3

⇒3 = H'/3

⇒H' = 3 * 3

⇒ H' = 9 cm

Answer 2

Answer:

9cm

Explanation: