The quantity Z is called impedence, and it represents effective resistance to the current flow. In complex number representation we may write

Then the combinations of impedences is analogou to those of Resistances. As an illustration the series L-C-R circuit solution can be obtained as follows :

Solved Problems

1. A resistance of 100 ohm is connected to a capacitance of 1 mf in series. Find the time constant of the circuit. If a 2 volt D.C. e.m.f. source is connected to the circuit, after how long the p.d. across capacitor will become 0.66 volt?

Solution

2. Find the condition for resonance of a series L-C-R circuit driven by A.C.e.m.f. source e = e₀    sin(wt).

Solution

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Index

26.1 R-C and L-R D.C Circuits
26.2 Reactance and impedance of L,C,R

Chapter 27