Optics Question 507

Question: A screen receives 3 watt of radiant flux of wavelength 6000 Å. One lumen is equivalent to $ 1.5\times {{10}^{-3}}watt $ of monochromatic light of wavelength 5550 Å. If relative luminosity for 6000 Å is 0.685 while that for 5550 Å is 1.00, then the luminous flux of the source is

Options:

A) $ 4\times 10^{3}lm $

B) $ 3\times 10^{3}lm $

C) $ 2\times 10^{3}lm $

D) $ 1.37\times 10^{3}lm $

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Answer:

Correct Answer: D

Solution:

$ \varphi =\frac{3}{1.5\times {{10}^{-3}}}\times 0.685 $

$ =1.37\times 10^{3}lumen $



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