Concepts Of Physics MCQ Edition [Volume 1]PhysicsPhotometry
Identify the correct statements from the following.
Options
- AThe luminous efficiency of a monochromatic source with a wavelength of 555 nm always exceeds that of a white l
- BThe illuminating power of a monochromatic source with a wavelength of 555 nm always exceeds that of a white li
- CThe luminous efficiency of a monochromatic source always exceeds that of a white light source having the same
- DThe illuminating power of a monochromatic source always exceeds that of a white light source having the same p
Correct answer
B. The illuminating power of a monochromatic source with a wavelength of 555 nm always exceeds that of a white li
Step-by-step solution
The relative luminosity of the human eye is maximum at a wavelength of 555 nm . Luminous efficiency is the ratio of total luminous flux to the total radiant power. For a monochromatic source of wavelength 555 nm , the luminous efficiency is maximum. A white light source contains various wavelengths across the visible spectrum, for most of which the relative luminosity is less than 1 . Thus, the overall luminous efficiency of a white light source is less than that of a monochromatic source at 555 nm . Illuminating p