now let's do the 5500K blub. first i took a picture at the WB setting that worked on the 3500K blub. look at the 1st pic here, the light is way blue, that means my actual color temp is a lot higher than the setting (which is 3700K). so i set my WB to sunny +0, which in the d40 equals to 5200K. 2nd pic shows the bulb is now white, so we have found a suitable match. 5200K is almost 5500K, which is what the bulb claims. another victory!
but you say, "comrad, i am so color blind that i couldnt even pass the driving exam, how can i REALLY make sure my picture looks white?" fear not, digital technology will give us the answer here. download GIMP if you dont have it already, it's a free version of photoshop. photoshop will work too, just dont pay $600 for it if you get it
open your picture in gimp, go to the histogram in the menu and then select RGB in the histogram window. 3rd picture shows where histogram is in the main menu. 4th picture is the histogram of the 1st picture, 5th is the hist of the 2nd pic. the one that has all colors overlaying eachother the closest is the whitest one.
why? because white color has equal parts red, green and blue light in it. when the amounts are not equal we see a diff color. so find a WB setting in your camera that produces the whitest image, make sure of that by looking at the RGB histogram, check what color temperature your camera's WB setting corresponds to and that will be a very close approximation of the actual color temperature of the light source.
btw, all pics are out of focus on purpose, i wanted to fill the whole frame with the light blub so that i dont throw off the overall average color balance of the picture by having something red or blue or something in the background.