What is the impedance across a resistor?

[Monsu]

hi, i want to ask, what is the impedance across a resisitor? isn't it just the value of the resistor? say i have a resistor of 50ohms, then its impedance is 50ohms, right??
thanks!

 

[garytse86]

http://en.wikipedia.org/wiki/Impedance

 

[pack_rat2]

Yes, it's 50 ohms. It's common practice (such as in audio and radio technology) to refer to a pure resistance as an "impedance." It's technically correct, since a pure resistance is just an impedance where X = j0. There's something that should be mentioned, though. Sometimes, real-world resistors may exhibit excessive reactance for a particular application. For instance, you can't use a 50 ohm wirewound resistor as an RF dummy load--it has too much inductance.