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A screen is placed 90cm from an object. ...

A screen is placed 90cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20cm. Determine the focal length of the lens.

A

21.4 cm

B

26.25 cm

C

`-21.4` cm

D

`-26.25` cm

Text Solution

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The correct Answer is:
A
21.4 cm
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KUMAR PRAKASHAN-RAY OPTICS AND OPTICAL INSTRUMENTS-SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs FROM .DARPAN. BASED ON TEXTBOOK)(MCQs BASED ON TEXTUAL ILLUSTRATION AND EXERCISE)
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  3. A small candle, 2.5 cm in size is placed at 27 cm in front of a concav...

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  4. A 4.5 cm needle is placed 12 cm away from a convex mirror of focal len...

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  6. A small bulb is placed at the bottom of a tank containing water to a d...

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  9. A small telescope has an objective lens of focal length 144cm and an e...

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  12. A small pin fixed on a table top is viewed from above from a distance ...

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  15. At what angle should a ray of light be incident on the face of a prism...

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