If a light source provides 2 Lux at 20 feet, how much Lux is expected at 10 feet?

To understand how the Lux level changes with distance from a light source, it's important to apply the concept of the inverse square law. The law states that the illuminance (Lux) from a point light source is inversely proportional to the square of the distance from the source. This means that if you reduce the distance from the light source, the amount of Lux will increase significantly.

In this case, if the light source provides 2 Lux at 20 feet, the distance is halved when considering 10 feet. The formula to calculate the change in illuminance based on distance is:

( Lux_1 \times \left( \frac{D_1}{D_2} \right)^2 )

Here, ( Lux_1 ) is the initial illuminance (2 Lux at 20 feet), ( D_1 ) is the initial distance (20 feet), and ( D_2 ) is the new distance (10 feet).

Applying the formula:

1. Initially, at 20 feet:

• Lux = 2

2. At 10 feet, using the distances:

• ( Lux = 2 \times \left( \frac{20}{10} \right)^2 =