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An object is placed at a distance of 30 ...

An object is placed at a distance of 30 cm from a concave lens of focal length 15 cm. What is the height of the object if the height of the image is 3 cm ?

A

3 cm

B

1 cm

C

6 cm

D

9 cm

Text Solution

Verified by Experts

The correct Answer is:
D
`u=-30 cm and f=-15 cm`
`because (1)/(v)-(1)/(u)=(1)/(f)`
`therefore (1)/(v)=(1)/(u)+(1)/(f)= -(1)/(30)-(1)/(15)`
`= -[(1)/(30)+(1)/(15)]=-(1)/(10)`
`therefore v=-10 cm`
and `(v)/(u)=(10)/(30)=(1)/(3)=(I)/(o)`
`therefore ` Height of the object `=3xx3=9` cm
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