The set of variables is a hybrid set that may include both currents and voltages. They are the inductor currents and the capacitor voltages. Each of these quantities may be used directly to express the energy stored in the inductor or capacitor at any instant of time. They collectively describe the energy state of the system. They are called the state variables

In the chapter, we shall define the basic active and passive circuit models, explain power conventions and determine when power is delivered and absorbed, state Ohm's law and Kirchhoff's law, determine the equivalent resistance of a passive circuit containing only resistors

1. Establish a normal tree. tree branches--Us, C(, R) cot ree(chords)-i,,(, R) 2. Assign voltage and current variables. Assign a voltage (with polarity reference) to every capacitor and a current(with arrow) to every inductor; there are the state variables. Indicate the voltage across every tree branch and the current through every link in terms of the source voltages, source currents,and the state

We consider each term of the Fourier aeries representing the voltage as a single source. The equivalent impedance of the network at no is used to compute the current at that harmonic. XL(n) =noL and XC() =-1/noC The sum of these individual responses is the total response i

We define the unit impulse as a function of time which is zero when its argument, generally (t-o), is less than zero; which is also zero when argument is greater than zero; which is infinite when its argument is zero; and which has unit area

Example 2: (p175-12) resistor, capacitor, and voltage source=100cos300n are all in series. If the average power dissipated by the resistor is 150W and the rms capacitor voltage is 10v, determine R and C

Any periodic waveform f(t)f(t) can be expressed by a Fourier series provided that (1) If it is discontinuous, there are only a finite number of discontinuous in the period T (2)It has a finite average value over the period T (3)It has a finite number of positive and negative maximums in the period T

The readings of three watt-meters Ax =v an+lnx vBx=vbn+lnx vc=von+v Nx (UANia tUBvibB+Uvicdt+l(uN(ia tibB +ic)dt T Jo aNaA foBNLbB +Uvic)dt The sum of the average powers taking by the three-phase loads

反谓反馈，就是将放大器的输出量(电流或电压)， 通过一定的网络，回送到放大器的输入回路，并同输 入信号一起参与放大器的输入控制作用，从而使放大 器的某些性能获得有效改善的过程

近似计算 为了分析计算公式的一致性和反映四种反馈组态的 特点，定义不同的增益和反馈系数。 一、串联电压负反馈 如图6―12(a)所示，串联电压负反馈的增益和反馈系数的定义为