Answer / dhinakaran.s

Impedance describes a measure of opposition to alternating
current (AC). Electrical impedance extends the concept of
resistance to AC circuits, describing not only the relative
amplitudes of the voltage and current, but also the
relative phases. When the circuit is driven with direct
current (DC) there is no distinction between impedance and
resistance; the latter can be thought of as impedance with
zero phase angle.

The symbol for impedance is usually and it may be
represented by writing its magnitude and phase in the form .

1.The magnitude of the complex impedance is the ratio of
the voltage amplitude to the current amplitude.
2.The phase of the complex impedance is the phase shift by
which the current is ahead of the voltage.
3.The ratio between resistance and Reactance.

SI unit is Ohm.
In AC circuit, Z=V/I Ohms.

Answer / k.prakashchandra

The' AC resistance 'is called impedance.It is also measured
in ohms.

i karmveer bharti persuing b.tech . plz send me syllabus and name of reference books. for preparation of section eng.

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