An array is a special variable, which can hold more than one value at a time. If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:
milliamps or watt/volt. The SI base unit for electric current is the ampere. 1 ampere is equal to 1000 milliamps, or 1 watt/volt. Note that rounding errors may occur, so always check the results. Use this page to learn how to convert between milliamperes and watts/volt. Type in your own numbers in the form to convert the units!
400w HPS = 50000 lumens = 125 lumens/watt. 600w HPS = 90000 lumens = 150 lumens/watt. So you can see that HPS is more efficient than CFL...and as you get into bigger HPS bulbs, it becomes a lot more efficient. There's also fewer hassles with multiple cords and saved money on your energy bill. PAR watt directly indicates how much light energy is available for plants to use in photosynthesis. The output of a 400 watt incandescent bulb is about 25 watts of light, a 400 watt metal halide bulb emits about 140 watts of light.