Question

Q3. A concave lens of focal length 15 cm 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

Explanation:

f= -15 cm

v= -10 cm

u= ?

1/v - 1/u = 1/f

1/f - 1/v = 1/u

1/-15 - 1/-10 = 1/u

1/-15 + 1/10 = 1/u

-2+3/30=1/u

1/30 =1/u

u=30 cm

Answer 2

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