Qstnid -Iv-12-light From A Point Source Falls On A Small Area Placed Perpendicular To The Incident Light. If The Area Is Rotated About The Incident Light By An Angle Of 60°, By What Fraction Will The Illuminance Change? - 22: Photometry

with Solutions - page 3

#12
Light from a point source falls on a small area placed perpendicular to the incident light. If the area is rotated about the incident light by an angle of 60°, by what fraction will the illuminance change?
Ans : If the area is rotated about the incident light by any angle, the illuminance will not change.
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