A light bulb illuminates a surface a distance 1.0 meter away with an illuminance of 1800 lux. What would be the illuminance on a surface 4.0 meters away if illuminated by the same bulb?

Explanation:

Here, for the Intensity due to bulb

Intensity = Power/(4pi * r^2)

Now, for the bulb with double power

the illuminance will be 2 times

new illuminance = 2 * 1800 lux

new illuminance = 3600 lux

i'm only doing this for the points : (

explanation:

i'm only doing this the points

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.