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UPSC Combined Geo-Scientist

Chemist

  • 2 objective papers
  • 120 questions each
  • 2 h per paper
  • 100 + 300 marks

Prelims Paper I covers general studies.

UPSC Combined Geo-Scientist, Prelims · 2025 · Paper I, General Studies · Q14 of 120

Geo-Scientist Prelims 2025 General Studies Q14: The focal length of a thin lens made up of glass of refractive…

QuestionOptics / lens maker's formula

The focal length of a thin lens made up of glass of refractive index 1·5 (see the figure below) having two centres of curvatures \(C_1\) and \(C_2\) with 15 cm and 30 cm as radii of curvatures respectively, would be

UPSC Combined Geo-Scientist Prelims 2025 Paper I (General Studies), Q14: figure printed with the question
  1. (a) 45 cm
  2. (b) 10 cm
  3. (c) 60 cm
  4. (d) 6 cm

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