Power to Load

To deliver the desired power to the $8\Omega$ load we will have to determine the amount of current and/or voltage we need at the load. Recall that the expression for average power is

$$P_L=\frac{1}{T}\int^T_0 V(t)I(t)dt$$ (57)

If we take our signals to be sinusoidal, then the integral leads to the following expression for power dissipated in the speaker:

$$P_L=\frac{V_o^2}{2R_L}$$ (58)

where V_o is the amplitude of the signal and R_L is the resistance of the speaker. $R_L=8\Omega$.Using the above expressions, we find that to deliver 6 watts to an $R_L=8\Omega$ speaker, we require to drive the load by a sinusoidal voltage with amplitude of approximately 10V.