BASE FORMULAS P=I*E E=I*R TO FIND VOLTAGE E=P/I E=I*R E=SQR(P*R) TO FIND CURRENT I=P/E I=E/R I=SQR(P/R) TO FIND POWER P=I*E P=E2/R P=I2*R TO FIND RESISTANCE R=E2/P R=E/I R=P/I2
P = Power in Watts E = Electromotive Force in Volts I = Electrical Current in Amps R = Electrical Resistance in Ohms SQR = Square Root
20 volts to a 4 ohm load is 100 watts, 20 volts to a 2 ohm load is 200 watts. Take your voltage figure and multiply it by itself (20V in this case so it's 20 X 20) then divide it by your ohm load. If you're running bridged to a 4 ohm sub say, you have to divide by 2 because the load presented to your amp is technically a 2 ohm load (doesn't apply to mono amps). That's the basic write up of this formula presented above TO FIND POWER P=I*E P=E2/R P=I2*R