The series combination of a resistor and capacitor has a greater practical importance than does the combination of a resistor and an inductor

The complete response=the natural response+forced response

The over-damped response---- i()= A,+A, The critically-damped response-- i(t) =e (At+A2) The under-damped- response---it)e-(b1 cos+2 sino)

In either case, leading or lagging, we say that sinusoids are out of phase () if phase angles equal they are said to be in phase(同相)

The effective value of any periodic current is equal to the value of the direct current which flowing through a resistance R, delivers the same power to r as periodic current does

sinusoidal current or voltage at a given frequency is characterized by only two parameters an amplitude and a phase angle. The complex representation of the voltage or current is also characterized by these same two parameters

We define the ratio of the phasor voltage to the phasor current as impedance

8-2 Superposition, source transformation and Thevenin's theorem Superposition:

《电路》（英文版）9-1 Instantaneous power

We assume=Im cos(t+a)i=Im cos(ot+B) The phase angle by which the voltage leads