volts,amps, watt question

[Larry Woods]

on a wall transformer it might read output 3.9 volts dc and 420 mamps out put and 120v/6.7 watts input. On a resistor the ohms are givwn with a watt rating ie 1/4 watts.<p>Is the watt rating mean the maximum you can put through it?? For a wall charger does that mean thats a limit it will deliver and for a resistor or other device does that mean it is the maximum you can put through it without failure?<p>Am I close?
Thanks people.

[cato]

Thats what it means...actually, in the wall wart example it probably also means thats the power you can draw without damaging the device....there is also and if/then relationship implied....if you draw the full 420 ma then on the input side it will consume 6.7 watts from your local power company.

[chessman]

And remember, with the wall wart you can draw a higher current for a short period of time without damage.