Q.7 Discuss the flow of A.
C through RC series circuit Also discuss the power
Iossesy impedance tringle and Q-factor for a given RL circuit.
R.C Series A.C. Circuit:
In RL-series circuit, the voltage V will be the phasor sum of
the two component voltage VR and VL. In order to draw a
vector diagram we found the current is common and can
therefore be used as the reference source because the
same current flows through the resistance and
capacitance. The individual vector diagrams for a pure
resistance and a pure capacitance is shown in figure.
The voltage drop VR (= IR) is in phase with current and is
represented by the phasor OA. The voltage drop Vc (= IXc)
Iags behind the current by 90° and is represented in
magnitude and direction by the phasor AB. The applied voltage V is the phasor sum
of these two drop i.e.
The quantity "R" + �9" offer opposition to current flow and is called impedance of
the circuit.
I = V/Z
Where Z=
The phasor diagram shows that circuit current I leads the applied voltage V by φ
This fact is also illustrated in the wave diagram and impedance triangle (as shown
in figure (b) of the circuit.
R-C Series Impedance Triangle:
The value of the phase can be determined as under: V
tan Φ =
- tan Φ = -
Power in R.C. Circuit:
The equation for voltage
and current are:
V = Vm sin ωt
And Im = sin (ωt + Φ)
So, the average power,
<P> = <V> <I>
<P>= VI cos Φ
