Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
Concepts Of Physics MCQ Edition [Volume 1]PhysicsPhotometry

A source uniformly radiates 31.4 W of radiant flux in all directions. If the luminous efficiency is 60 lumen watt ⁻¹ , determine the luminous intensity of the source.

Options

  1. A600 cd
  2. B300 cd
  3. C1884 cd
  4. D150 cd

Correct answer

D. 150 cd

Step-by-step solution

Total luminous flux = Radiant flux Luminous efficiency = 31.4 60 = 1884 lm For a source radiating uniformly in all directions, the total solid angle is 4 sr . Luminous intensity I = 4 I = 1884 4 3.14 = 1884 12.56 = 150 cd

Practice Photometry on Quantrex Academy →

More from Photometry

Calculate the radiant flux of a source if it emits 45 joules of energy over a period of 15 s .When exposed to a 10 W source for 12 s , a photographic plate records sufficiently intense lines. To obtain equally intense lines, what should be the exposure time for a 12 W sourcBased on the relative luminosity curve shown in the figure, determine the relative luminosity of wavelength 580 nm .Based on the relative luminosity curve shown in the figure, determine the relative luminosity of wavelength 520 nm .Based on the relative luminosity curve shown in the figure, determine the relative luminosity of wavelength 600 nm .The relative luminosity for a wavelength of 600 nm is 0.6 . Determine the radiant flux at 600 nm required to generate the same brightness sensation as that produced by a radiant flBased on the relative luminosity curve shown in the figure, determine the relative luminosity of wavelength 480 nm .A monochromatic source of 1 W produces a luminous flux of 450 lumen . Determine the relative luminosity at the emitted wavelength. Full Photometry list All Concepts Of Physics MCQ Edition [Volume 1] PYQs