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JEE Main 2020 (8 Jan, Shift 1) · Optical Instruments & the Eye

Optical Instruments & the Eye question from JEE Main 2020 (8 Jan, Shift 1)

Q29JEE Main 2020 · 8 JAN · SHIFT 1Easy

Optical Instruments & the Eye

The magnifying power of a telescope with tube 60 cm is 5. What is the focal length of its eye piece?

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Answer: (b)

  1. fo+fe=60 cmf_o + f_e = 60\,\text{cm} and fo=5fef_o = 5f_e.
  2. 6fe=60⇒fe=10 cm6f_e = 60 \Rightarrow f_e = 10\,\text{cm}
  3. So the answer is (b) 10 cm.
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