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Concepts Of Physics MCQ Edition [Volume 1]PhysicsPhotometry

A monochromatic source of 1 W produces a luminous flux of 450 lumen . Determine the relative luminosity at the emitted wavelength.

Options

  1. A152 %
  2. B45 %
  3. C81 %
  4. D66 %

Correct answer

D. 66 %

Step-by-step solution

The maximum luminous flux for a 1 W source is 683 lumen (which occurs at a wavelength of 555 nm ). The relative luminosity is defined as the ratio of the luminous flux at the given wavelength to the maximum luminous flux for the same power. Relative luminosity = 450 683 100 % Relative luminosity 65.88 % 66 %

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