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9. Ray optics abd optical instruments — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics9. Ray optics abd optical instruments1 Mark
MCQ
Missing lines in a continuous spectrum reveal
  • A
    Defects of the observing instrument
  • B
    Absence of some elements in the light source
  • C
    Presence in the light source of hot vapours of some elements
  • ✓
    Presence of cool vapours of some elements around the light source
✓

Answer

Correct option: D.
Presence of cool vapours of some elements around the light source
d
When a continuous spectrum is passed through a material, some wavelengths are absorbed and thus some dark lines are formed which is called line spectrum.

This absorption is caused due to the presence of cool vapors of some elements which absorb the energy of the wavelengths.

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