why are some things measured in volt-amperes. thats just a watt

about volt-amperes and how they differ from watts in the context of AC power 

@codl when talking about AC power, there are three different quantities at play

Watts measure real power consumed, the power that actually gets converted to heat and/or useful work

Volt-amperes measure apparent power, the product of RMS current and RMS voltage, which is equal to the real power only in the case of a purely resistive load. Anything supplying AC power (inverters, generators, transformers) will be rated in VA, as that's what directly affects the losses in the power supply

Then there's VAR for "volt-ampere reactive", which just measures reactive power and not real power. Reactive power can be thought of as the energy that "sloshes" back and forth between the source and the load, doing no useful work (but contributing to transmission losses since it does increase current draw)

The relationship between the three mathematically S = √(P²+Q²), where S is apparent power, P is real power, and Q is reactive power.

-F

@Felthry right i keep forgetting that ac circuits are complicated and that i don't understand them

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@codl If you want help understanding them, feel free to ask! but if you don't want help just know that VA and W are indeed the same dimension, but are used to measure different things. Similar to how Hz and Bq are equal units but used to measure different things.
-F

@codl Becquerel. In the context of nuclear physics, it's used to measure activity of a radioactive sample, 1 Bq is one decay per second (averaged)
-F

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