Question

The brightness of a source based upon sensation of eye is determined by:
A. Radiant flux entering the eye
B. Luminous flux entering the eye
C. Wavelength of light
D. None of the above

Answer 1

Visible light is a form of electromagnetic (EM) radiation, as are radio waves, infrared radiation, ultraviolet radiation, X-rays, and microwaves. Generally, visible light is described because of the wavelengths which can be seen to maximum human eyes. EM radiation is transmitted in waves or debris at specific wavelengths and frequencies. This extensive range of wavelengths is called the electromagnetic spectrum. That spectrum is usually divided into seven regions so as to lower wavelength and increase energy and frequency.

Complete answer:
Only light of visible range excites the retina of the eyes. The range of Light, which human eyes can sense, is called Luminous of light. The objects that could emit light energy through themselves are called luminous items. Objects just like the sun that deliver out or emit light on their own are luminous items. Other examples of luminous bodies are Electric bulbs, torches, etc.

Luminosity refers to the entire quantity of energy produced through distinct celestial bodies (stars, galaxies) according to unit time and it is largely measured in joules per second or watts in SI units. We can outline luminosity as: the absolute degree of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object.

So, option B is correct.

Note: All electromagnetic radiation is light, however, we will only see a small part of this radiation—the component we name visible light. Cone-shaped cells in our eyes act as receivers tuned to the wavelengths on this slender band of the spectrum. Other quantities of the spectrum have wavelengths too big or too small and energetic for the biological obstacles of our perception.