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Formulas for Volts = watts and other equations

Posted: Thu Sep 20, 2007 10:27 am
by Tim A
Someone please post them in here with an example. I'd like to see:

Volts = watts at a given impedance.

Any other useful equations.

Posted: Thu Sep 20, 2007 10:58 am
by Bill Fitzmaurice
Ohms Law. No need to reinvent it.

Posted: Thu Sep 20, 2007 11:00 am
by Tim A
Bill Fitzmaurice wrote:Ohms Law. No need to reinvent it.
No, just a need to spell it out for those of us who don't know it.

Posted: Thu Sep 20, 2007 11:39 am
by Bill Fitzmaurice
http://www.grc.nasa.gov/WWW/K-12/Sample ... mslaw.html
Also helpful to know that watts = volts x amps.
In a speaker system volts = the square root of watts x impedance.

Posted: Thu Sep 20, 2007 11:41 am
by SoundInMotionDJ
V = IR (Ohms Law)

W = V**2 / R = I**2 R

Where:

V - volts
I - current (amps)
R - resistance (Ohms)
W - watts



Resistance in Series:

Rs = R1 + R2 + ... + Rn

Resistance in Parallel:

1 / Rp = 1/R1 + 1/R2 + 1/R3

For the same resistance values:

Rp = R / n

For different resistance values (3 shown):

Rp = ( R1 * R2 * R3 ) / (R1*R2 + R2*R3 + R1*R3 )


So, to answer Tim's question:
Volts = watts at a given impedance.
V = sqrt( WR ) = sqrt(W) * sqrt(R)

--Stan Graves

Posted: Thu Sep 20, 2007 11:43 am
by LelandCrooks