I am having trouble understanding when to use $\theta = \omega t$ and when to use the $\tan \phi = \frac{X_L-X_c}{R}$.
Do we only use the $\tan \phi = \frac{X_L-X_c}{R}$ when dealing with series RLC circuits? Do we use the $\theta = \omega t$ equation when dealing with any other circuit?
Best Answer
The phase angle of the current/voltage in a circuit having inductance, capacitance or both will be different from the phase angle of the current/voltage generated by the source. In such a case the phase angle of the voltage or current from the source will be found by using the formula: $$\theta = \omega t$$
The phase angle of the current or voltage in the circuit or through the passive circuit elements(R/L/C) will be found by the formula:
$$\theta = \tan^{-1}(\frac{X_L -X_c}{R})$$