00:01
Okay, so for this problem, we want to first get the luminous efficiency if we have 100 watt and 1 ,700 lumine bulb.
00:10
And so we're told that the luminous efficiency is the ratio of the flux to the power input.
00:19
So that's going to be 17.
00:22
So the flux is 1 ,700 lumens.
00:27
And then the power is 100 watts.
00:30
So that's going to be 17 lumens per watt.
00:37
And then for part b, we want to get how many lamps to light up this factory.
00:44
And we know that the lamps are 40 watts and then 60 lumens per watt.
00:55
And so then we can say that each bulb is going to do 2 ,400 lumens just by most.
01:03
Applying these two, given that, you know, for one watt, there's 60 lumens, and then there's 40 watts, so therefore there's 240, 240, 2 ,400 lumens per bulb.
01:14
And then, and then we can kind of figure out, i forgot what this is called.
01:21
Oh, an illuminance.
01:22
So we can get the illuminants of a single bulb by dividing it by the square, by the area of the floor, which is 25 times 30 meters.
01:39
So that's going to be per bulb...