I am very new to electronics, and literally have had my arduino for about a week. I have an old Linksys power adapter that fits the barrel jack and has an output of 12 volts and 0.5 amps. It also says that it is a switching power supply (I have no idea what this is), I don't want to damage the arduino, so would it be safe to just plug this in as is, or what should I do? Thanks for your help.
it says 12volts DC right? is the center of the plug +?
if so then yes it will be ok
You should indeed always double check, but if you're using the Official Arduino board, there's a built in diode that keeps you from burning things out when using the 2.1mm power jack.
Keep in mind that this Diode does NOT protect against reverse polarity when using the VIN and GND pins.
Thanks both of you, I love the fact that there is a great community here.
for the second question, switching
there are a couple ways to bring down power, 1 is to use a transformer, a pair of coils set near each other, depending on how much wire you have coiled up on each side the magnetic forces tween the 2 induct current giving you the desired voltage, this is fairly wasteful, and the transformer itself is fairly large / heavy
a switching adapter switches the current on and off in a technique called PWM, which you will learn about while using arduino, then averaged out in a analogue filter (ie a resistor-capacitor setup) to make a constant average voltage
switching power supplies can deliver greater power for their size, for example I have a 1 amp transformer supply and its the size of a potato, where as a switching supply I have can provide 2x as much current at the same voltage and its small enough to fit in a pack of cigarettes
switching supplies have their downsides, but the most compelling downside I have been told is from a old school audiophile recording studio repair tech, whom fussed about the switching noise being passed to analogue systems as he was flicking a tube with an obvious 60hz hum in the system, so whatever lol (that is a ford / chevy debate, like religion and politics, you cant win)