[ELECTRON] Resistor Question

[Gordon JC Pearce]

On Fri, 2010-04-02 at 00:41 +0000, Chris MacInnes wrote:
> Hi everyone, this is probably a stupid question.
> 
> 
> I am working from a schematic and after each resistor it says either
> '1/4w' or '1/2w' like this: 47K 1/4W Resistor.
> 
> 
> Can anybody explain to me what this means?
> 

It's the power rating.  As resistors dissipate electrical power as heat,
they need to be sized to suit the amount of power they're going to
dissipate.  You can work this out from Ohm's Law, with either P=V^2/R or
P=(I^2)R.  Mostly you won't need to, because the vast majority of
resistors you will use will be 1/4W or even less.

Gordon MM0YEQ