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JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
The magnifying power of a telescope with tube \(60\; \mathrm{cm}\) is \(5 .\) What is the focal length of its eye piece?......\(cm\)
- A \(30\)
- B \(40\)
- C \(20\)
- D \(10\)
Answer & Solution
Correct Answer
(D) \(10\)
Step-by-step Solution
Detailed explanation
\(\mathrm{L}=\mathrm{f}_{0}+\mathrm{f}_{\mathrm{e}}=60\; \mathrm{cm}\) \(\mathrm{M}=\frac{\mathrm{f}_{0}}{\mathrm{f}_{\mathrm{e}}}=5\) \(\Rightarrow \mathrm{f}_{0}=5 \mathrm{f}_{\mathrm{e}}\) \(\therefore \quad 6 \mathrm{f}_{\mathrm{e}}=60 \mathrm{cm}\)…
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