Question

The illuminance on a surface is 6 lux and the surface is 4 meters from the light source. What is the intensity of the source?

A. 24 candelas
B. 144 candelas
C. 72 candelas
D. 96 candelas

Answer 1

Answer: D. 96 candelas

Step-by-step explanation: Illuminance is defined as the quantity of light incident on a surface per unit of area. It depends on the light’s intensity and its distance from the surface.

E= illuminance on the surface (in lux)= 6 lux

I = the intensity of the light from the source (in candelas) = ?

S= distance from the light source to the surface (in meters) = 4 m

`E=(I)/(S^2)`

`I=E* S^2`

`I=6* (4)^2=96candela`