8/3 What's the relationship between WATT, VOLT, and AMP? I have a power
supply that is 12V and 2.1Amp, but it is unable to drive a bulb
that is 12V and 55Watts. I know there is not enough ampere in the
power supply, but how do you derive the relationship?
\_ power[Watts] = voltage[Volts] * current[Amps].
also note that if you're dealing with AC, the current and voltage
are RMS, not peak to peak.
\_ 12V, battery power, hence DC. What's RMS? Richard Stallman?
Average power?
\_ rms:rms and an internet worm will get you into any host!
\_ Root Mean Square
\_ yes, and from a practical standpoint, for sinusoidal ac
currents, it's a factor of 1/sqrt(2) different from peak
to peak for voltage, and hence a factor of 2 different
in power.
\_ thank you. So 12V*2.1Amp=25Watts, and I'm ~2.5 Amps short of
driving the 55W bulb, right?
\_ Watts is a measurement of power. You can measure your car's
horsepower in Watts.
You can think Amp as measurement of flow rate, similiar to
how fast water flows out of the toliet water tank when you flush.
Voltage is pressure. In order to have water flow from one
place to another, it need to have differences in pressure.
\_ What the "VA" used in the battery backup specifications mean?
Tricky part is to get a feel of what are these units. For
example, one Amp is HUGE amount of electricity flow, even with
reasonably small voltage, it may kill you.
\_ "it's volts that jolts and mils that kills" |