NEET-XII-Physics
22: Photometry
- #7A light source emits monochromatic light of 555 nwavelengthm. The source consumes 100 W of electric power and emits 35 W of radiant flux. Calculate the overall luminous efficiency.Ans : Given:
Wavelength of light, `` \lambda `` = 555 nm
Radiant flux emitted = 35 W
Power input = 100 W
Overall luminous efficiency = `` \frac{\,\mathrm{\,Total\,}\,\mathrm{\,luminous\,}flux}{\,\mathrm{\,Power\,}input}=\frac{35\times 685}{100}=239.75\,\mathrm{\,lm\,}/\,\mathrm{\,W\,}``
So, the overall luminous efficiency will be 240 lm/W.
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