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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2022 · Mains Paper III

Q5(c). Double-beam flame atomic absorption spectrophotometer

Question

Draw a schematic diagram representing a typical double beam design of a flame type spectrophotometer used in AAS instrument.

Answer in brief

A rotating sector mirror sends the lamp beam alternately through the flame (P) and round it (Pr); one detector measures both beams and the readout is A = log(Pr/P).

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The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

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Topic notes: spectroscopic instruments (Beer–Lambert law, UV–vis and IR instruments, Job's method, AAS and flame emission), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversdouble beam AAShollow cathode lamprotating sector mirror chopperflame atomic absorptionphotomultiplier

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