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A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. |
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Answer» `O = 4.5 cm, u = -12cm, f = 15 cm` `(1)/(u)+(1)/(upsilon)=(1)/(f) rArr (-1)/(12)+(1)/(upsilon)=(1)/(15)` `(1)/(v)=(1)/(12)+(1)/(15)=(5+4)/(60)=(9)/(60)=(3)/(20)` `upsilon=(20)/(3)=6.7cm` Image is virtual and erect and is formed behind the mirror. `(I)/(O)=(-v)/(u) rArr (1)/(4.5)=(-20)/(3xx(-12))` `I=(20xx4xx2)/(3xx12xx10)=2.5cm` As the needle is moved further from the mirror, the image moves towards the focus and gets progressively diminished in size. |
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