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Directions (Q. No. 6 to 10):

Read the following text and answer the following questions on the basis of the same:

Photometry:

The measurement of light as perceived by human eye is called photometry. Photometry is measurement of a physiological phenomenon, being the stimulus of light as received by the human eye, transmitted by the optic nerves and analysed by the brain. The main physical quantities in photometry are (i) the luminous intensity of the source, (ii) the luminous flux or flow of light from the source and (iii) illuminance of the surface. The SI unit of luminous intensity (I) is candela (cd).

The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency \[540\text{ }\times \text{ }{{10}^{12}}\] Hz and that has a radiant intensity in that direction of 1/683 watt per steradian, If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted into that solid angle is one lumen (1m). A standard 100 watt incandescent light bulb emits approximately 1700 lumens.

What is photometry?

A) Measurement of light as perceived by human eye

B) Measurement of number of photons emerging from a light source

C) Measurement of electrons emitted by photosensitive surface

D) Measurement of photosensitivity