Imagine that youve just received a promotion at work. While your new office is being renovated, you will need to spend just a few weeks working in a storage area re-purposed to be a temporary office. An office assistant will have their desk in this temporary space as well. There are no windows, just two desks in a small space, and only one source of light; an LED light fixture suspended from the roof of your office. The diagrams on the last page contain the dimensions and layout of your office. You decide to apply the concepts of illumination you learned in class to evaluate the lighting conditions of the room.The building manager who is helping you get set up mentions that he recently replaced all the incandescent (filament) bulbs in the building with these LED fixtures have saved the company a bunch of money. He mentions that the old incandescent bulbs were inefficient, only providing 15 lumens for every 1 Watt of electric power. He picks up an old incandescent bulb, which is labeled 100 W, holds it next to the light fixture, and exclaims: With the same power consumption, the new light fixture provides 5 times as much illumination as the incandescent bulb! I even checked with my photometer!

1) Assuming that the incandescent fixtures and LED bulbs are of similar shape and size, and have similar light-emission profiles, what would you estimate the total luminous flux of the LED bulb to be, in lumens? (3 points)

2) The LED fixture is spherical and hangs directly in the center of the room, inside of a frosted diffuser (see the diagram on page 3). The fixture hangs on a chain that such that its center is exactly 2.5 feet from the ceiling. The ceiling and walls around you are all painted a very dark color (maroon, of course). Compute the illuminance at the exact center of the top of your desk with this lighting configuration. (Assume the intensity of light is: 596.83 candela) (7 points)

3) What is the illuminance on the exact center of the top of the assistants desk? (5 points)4) When the LED is turned on and all other source of light in the room are off, it does not seem to be sufficient illuminance to support the work youll do, which could most accurately be referred to as Computer work. Referring to MIL-STD-1472G (in the lecture slides), does this meet the minimum illuminance required for this work? Please justify your answer with specific values. (5 points)

4) When the LED is turned on and all other source of light in the room are off, it does not seem to be sufficient illuminance to support the work youll do, which could most accurately be referred to as Computer work. Referring to MIL-STD-1472G (in the lecture slides), does this meet the minimum illuminance required for this work? Please justify your answer with specific values. (5 points)

Top view 2' 8' Luminous ceiling 3' x 5 chair Your desk LED 1.5 Assistant's desk 3' 4' 3' chair 15 Luminous ceiling - Front view 2.5 (LED 15' 3' 4' chair Your desk 3' Assistant's desk 15