Hey guys,
PPI Exam 1 question 16 is about the illuminance of a hemispheric lamp. Now I know that illuminance E is basically lumens over area (E = lm / A), but...
In the solution to this problem, when calculating area A = 0.5A sphere = 0.5 * 4 * pi * r^2, why is the distance d between lamp and ground used in place of the radius of the sphere area A = 4 * pi * r^2?
Thanks for any input on this.
PPI Exam 1 question 16 is about the illuminance of a hemispheric lamp. Now I know that illuminance E is basically lumens over area (E = lm / A), but...
In the solution to this problem, when calculating area A = 0.5A sphere = 0.5 * 4 * pi * r^2, why is the distance d between lamp and ground used in place of the radius of the sphere area A = 4 * pi * r^2?
Thanks for any input on this.
