Answer : Option D) 5 meters
Explanation :
To find the luminous intensity this formula is used;
Luminous intensity = illuminance × [tex]radius
^{2}[/tex]
∴ Lv = Ev × [tex] r^{2}[/tex]
We know the luminous intensity is 100 candelas and the illuminance is 4 lux.
∴ 100 = 4 x [tex] r^{2}[/tex]
∴ 100/4 = [tex] r^{2}[/tex]
∴ 25 = [tex] r^{2}[/tex]
∴ r =√25 = 5 meters
Therefore, the surface will be at a distance of 5 meters from the source.
