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A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is:

Asked in NEET 2024 · Telescopes

• (1) 17
• (2) 32
• (3) 34
• (4) 28

Step-by-step solution

Why the other options are wrong

• (1) No single slip gives 17; it is not (fₒ)/(fₑ) or any variant of it.
• (2) No single slip gives 32; (fₒ)/(fₑ)=28 and the near-point value is about 34.
• (3) This is the magnifying power with the final image at 25 cm, (fₒ)/(fₑ)(1+(fₑ)/D)=33.6. For a distant object in normal adjustment it is (fₒ)/(fₑ).

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