April 19th, 2020

illumination

One of the minor features of the new apartment is rows of light fixtures over both the kitchen and bathroom sinks. Despite this, both areas seemed rather gloomy, even with the lights on. Yesterday I bought two packages of LED bulbs, rated at 75 watts but actually using much less power than that, and installed them. Now each area has combined power consumption less than from one incandescent bulb, but the equivalent of 300 watts of luminous output. That's really bright and gives us high visibility, very helpful in areas where we want to get things clean, and also making the bathroom a place where I can read comfortably. Yay for technology!

I've read a historical study that cites people in the eighteenth century commenting on the blaze of light from a candelabra with a dozen candles. But a candle's output is (unsurprisingly) 1 candela, which is about the luminous output from a 1-watt incandescent bulb (1 candela is 1 lumen/steradian, and a full sphere has 4π steradians, so that's 14.6 lumens; incandescent bulbs have varying efficiency, but 14-16 lumens/watt is typical for 60-watt bulbs). So a dim 40-watt incandescent bulb is vastly brighter than that "blaze of light." And now that light level feels like being in a cave . . .