In the signal power equation
$$ P(g(t)) = \lim _{T\to \infty }{\frac{\left(\int_{-\frac{T}{2}}^{\frac{T}{2}}g\left(t \right)^2dt\ \right)}{T}} $$ What does the $T$ really represent ?
From my understanding, the target of the power equation is to get the average power throughout the signal, which is basically Energy / Time , so we divide the integral "Energy" over the time "T"$T$.
but i don't seem to understand why are we taking the limit of T$T$ to infinity at all ?
e.g. if the signal was a sine wave $$g(t)=\sin(t)$$ then using This calculator in desmos i found out that we only get the average power as 0.5 (the correct answer) if T$T$ was a multiple of the periodic time of the sine wave
so changing T$T$ to other values than multiples of the periodic time gives wrong answers, so why are we taking the limit to infinity at all ? or does T$T$ has another meaning ?
Edit 1:
Also, can we change the upper/lower bounds in the energy equation to $\int_0^T$ ?
i checked and they give the same value