应该注意：一个理想电压源(独立或受控)可向电路提供任意电流以保证其端电压为规定值，而电流源可向电路提供任意电压以保证其规定电流。A different class of relationship occurs because of the restriction that some specific type of network element places on the l another class of relationship is one between several variables of the same type which occurs as the result of the network configuration,i.e.,the manner in which the various element of the network are interconnected.一种不同类型的关系是由于网络元件的某种特定类型的连接对变量的.约束。
另一类关系由于网络结构，即网络的不同元件互相连接的方式所产生的相同形式的一些变量间的关系。1.A resistor whose resistances vary with its current is known as a nonlinear resistor.
open circuit is a circuit element with resistance approaching infinity.
electric heater draws 10A form a 120V resistance of the heater is 12Ω.
ideal dependent source is an active element in which the source quantity is controlled by another voltage or current.
independent voltage source is a two-terminal element,which maintains a specified voltage between its terminals.
rding to the passive sign convention,if the power has a plus sign,power is absorbed by the element.
tric current is the time rate of charge,measured in amperes.
a circuit containing N nodes and M branches,there will be N-1 independent node voltage.
a voltage source,its terminal voltage is known but its current must be determined by the external circuit connecting with it.
in an acb phase sequence,Uan=100∠-20°,then Ubn is 100∠100°.
is conventional to take the current flow as the movement of positive charges.
hhoff’s laws are that are based on the topology of the network.
hhoff’s current law can be stated in two ways.
hhoff’s current law is based on the law of conservation of charge.
hhoff’s voltage law is based on the law of conservation of energy.
analysis applies KVL to find unknown currents which are mesh currents.
l analysis is based on a systematic application of KCL,and satisfies automatically KVL.
l analysis method is choosing node voltages as circuit variables.
’s law states that the voltage across a resistor is directly proportional to the current flowing through the resistor.
stors are passive elements.
plus(+)and minus(-)signs in an electric circuit diagram are used to define voltage polarity.
e are four possible types of dependent source.
circuit element used to model the current-resisting behavior of a material is the resistor.
algebraic sum of all voltage around a loop is zero.
potential at reference node or datum node is zero in nodal analysis.
energy required to move a unit charge through an element is voltage.
voltage across an inductor eads the current through it by 90°.
voltage across an capacitor lags the current through it by 90°.
three-phase source and the three-phase load have four possible connections.
three voltages that have the same amplitude and frequencyωand are out of phase with each other by 120°are said to be balanced three-phase voltage.
