Page 300 - Basic Electrical Engineering
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all instants of time and has been shown in Fig. 3.13 (b). Power in a resistive
circuit is taken as the average power which is
Power in a resistive circuit,
Power factor is the cosine of the phase angle between voltage and current.
In a resistive circuit the phase difference between voltage and current is
zero, i.e., they are in phase. So the phase angle θ = 0.
Power factor, P f = cosθ = cos 0° = 1
AC applied across a pure inductor
A pure inductor means that the resistance of the inductor coil is assumed to
be zero. The coil has only inductance, L. Such an inductor is connected
across a sinusoidally varying voltage, v = V sin wt as has been shown in
m
Fig. 3.14 (a).
As a result of application of voltage, v an alternating current, i will flow
through the circuit. This alternating current will produce an alternating
magnetic field around the inductor. This alternating or changing field flux
will produce an EMF in the coil:
