Electrical Engineering ⇒ Topic : Phase angle

Phase angle. It is clear from eqs. (i) and (iii) that current lags behind the voltage by π/2 radians or 90⁰. Hence in a pure inductance, current lags the voltage by 90°. This is also indicated by the phasor diagram shown in Fig. (a). Note that r.m.s. values have been used in drawing the phasor diagram. The wave diagram shown in Fig. (b) also depicts that current lags the voltage by 90⁰. There is also physical explanation for the lagging of current behind voltage in an inductive coil. Inductance opposes the change in current and serves to delay the increase or decrease of current in the circuit. This causes the current to lag behind the applied voltage.

                                                         fig . (a)

                                                              fig. (b)