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?
If the area is rotated about the incident light by any angle, the illuminance will not change.

Question

If the area is rotated about the incident light by any angle, the illuminance will not change.

Philoid · Accepted Answer

If the area is rotated about the incident light by any angle, the illuminance will not change.