Telescope: choose your answer
Original set: 24 September 2026 · Publication edition: 25 September 2026
The resolving power of an astronomical telescope can be increased by
A. increasing the diameter of the objective lens
B. increasing the focal length of the objective lens
C. increasing the focal length of the eyepiece
D. decreasing the diameter of the objective lens
Choose before revealing the explanation.
Reveal explanation, sources and original-item counts
Answer: A — increasing the objective diameter.
Resolution means distinguishing two nearby directions as separate. For the same wavelength in the ideal optical model, a larger objective aperture improves resolution. Focal lengths instead set the telescope’s angular magnification in normal adjustment: |M| = fₒ/fₑ. Magnifying an unresolved image does not itself resolve its details. NCERT XII Physics, §9.7.2, pp 244–245
Observed September 24 responses: 2 correct, 12 wrong and 4 skipped; A 2 / B 10 / C 2 / D 0. Wrong among non-skipped answers: 12/14 (85.7%); wrong among all records: 12/18 (66.7%). Three responses with unknown content bindings are excluded. These counts do not reveal respondents’ reasoning.
Snapshot: September 25, 07:18 IST. Counts include partial attempts; accounts are not verified people, answer language is unknown, and late arrivals can change counts.
Editorial correction: the Hindi astronomical term is corrected from “ज्योतिषीय” to “खगोलीय”; option order and answer key are unchanged. The explanation states the fixed-wavelength, ideal-model and normal-adjustment conditions. This page does not claim a production-app correction.
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