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电路原理课件讲义英文版 Chapter_2汇总

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电路原理双语课件

电路原理双语课件

The transfer function can be written as
The transfer function H(ω) of a circuit is the frequency-dependent ratio of a phasor output Y(ω) (an element voltage or current) to a phasor input X(ω) (source voltage or current). Thus,
Vo 1/ jωC 1 H (ω ) = = = Vs R + 1/ jωC 1 + jω RC
The magnitude and phase of H(ω) are
Amplitude response 幅频特性
ω H= , φ = − tan 2 ω0 1 + (ω / ω 0 )
1
−1
where ω0 = 1/RC. At ω = 0, H = 1 and φ = 0. At ω = ∞, H = 0, and φ = − 90°. Also, at ω = ω0, H = 1/ 2 and φ = − 45°.
14.1 INTRODUCTION
In our sinusoidal circuit analysis, we have learned how to find voltages and currents in a circuit with a constant frequency source. If we let the amplitude of the sinusoidal source remain constant and vary the frequency, we obtain the circuit’s frequency response. The frequency response of a circuit is the variation in its behavior with change in signal frequency. The sinusoidal steady-state frequency responses of circuits are of significance in many applications, especially in communications and control systems.

电路原理课件 (2)

电路原理课件 (2)

Theories of Electrical Circuits Lecture 2 Tsinghua University 2007第2讲电阻、电源和基尔霍夫定律Theories of Electrical Circuits Lecture 2 Tsinghua University 2007•线性元件特性•独立源•受控源•基尔霍夫定律电阻电压源, 电流源KVL, KCLTheories of Electrical Circuits Lecture 2 Tsinghua University 20072.1 电阻元件(resistor)线性定常电阻元件:任何时刻端电压与其电流成正比的电阻元件。

1. 符号(1) 电压与电流取关联参考方向2.欧姆定律(Ohm’s Law)u =R i电阻R (resistance)单位名称：欧(姆) 符号: Ωk ΩM ΩR +uiRTheories of Electrical Circuits Lecture 2 Tsinghua University 2007令G =1/RG 称为电导(conductance)则欧姆定律表示为i =G u单位名称：西(门子) 符号: S (Siemens)R ∝tg α♦线性电阻R 的电阻值是一个与电压和电流无关的常数。

线性电阻元件的伏安特性为一条过原点的直线αuiG+uiTheories of Electrical Circuits Lecture 2 Tsinghua University 2007(2) 电阻的电压和电流取非关联参考方向R (G )+ui则欧姆定律写为u =–Ri i =–Gu♦公式必须和参考方向配套使用！Theories of Electrical Circuits Lecture 2 Tsinghua University 20073. 功率和能量p 吸=–ui =–(–R i ) i =i 2R=–u (–u/ R ) = u 2/ Rp 吸=ui =i 2R =u 2/ R功率：R+uiR+ui能量：可用功率表示。

《电路原理》第一章 电路模型和电路定律 (2)

《电路原理》第一章 电路模型和电路定律 (2)

理想电流源的电压、电流关系 ①电流源的输出电流由电源本身决定，与外电路无
关；与它两端电压方向、大小无关。
返回 上页 下页
u
②电流源两端的电压由电源及外电路共
iS
同决定。
直流电流源的
例
伏安关系
0
i
+ iS
u
R
-
u RiS u 0 (R 0)
u (R )
外电路
电流源不能开路！
t0
uidξ
t0
无源元件、耗能元件
1.6 电压源和电流源
分类：
独立电源
(independent source)
电压源 电流源
受控电源
(dependent source)
1.理想电压源
定义
其两端电压总能保持定值或一定 的时间函数，其值与流过它的电 流 i 无关的元件叫理想电压源。
电路符号
i
+
_
1. 电流的参考方向 (current reference direction)
电流
带电粒子有规则的定向运动
电流强度
单位时间内通过导体横 截面的电荷量
def Δ q dq i(t) lim
Δ t0 Δ t dt
单位： A（安培）、kA、mA、A
方向：规定正电荷的运动方向为电流的实际方
+
us _
u
+
u uS RSi
u us
RS
_
O
i
考虑内阻
一个好的电压源要求 RS 0
实际电压源也不允许短路。因其内阻小，若 短路，电流很大，可能烧毁电源。
2.理想电流源

电路基础理论英文版课件第一章

电路基础理论英文版课件第一章
Measurement
Resistance is measured in ohms (Ω) using a ohmmeter.
Definition
Definition
Capacitance is the ability of a capacitor to store electrical energy. It is measured by the capacity of the capacitor to hold a charge.
详细描述
04
Analysis methods for circuits
单击此处添加正文，文字是您思想的提炼，为了最终呈现发布的良好效果，请尽量言简意赅的阐述观点；单击此处添加正文，文字是您思想的提炼，为了最终呈现发布的良好效果，请尽量言简意赅的阐述观点；单击此处添加正文，文字是您思想的提炼，为了最终呈现发布的良好效果，请尽量言简意赅的阐述观点；单击此处添加正文 10*16
A circuit that allows the flow of AC current, typically used in household and industrial applications.
பைடு நூலகம்
Definition of Circuit
Components
01
Circuit components include resistors, capacitors, inductors, diodes, transistors, and power sources. These components are connected to form a complete circuit.
contents
目 录

电路与电子技术课件(英文版)-第一章 电路的基本概念

电路与电子技术课件(英文版)-第一章 电路的基本概念

Topics Covered
Week 1
Week 2
Monday Nov. 25, 2019
Tuesday Nov. 26, 2019
Friday Nov. 29, 2019
Monday Dec. 2, 2019
Tuesday Dec. 3, 2019
Friday Dec. 6, 2019
Fundamentals of Electric Circuits: Elements of electric circuits; Kirchhoff’s law; Voltage/Current divider laws; Series and parallel circuits
10
Alessandra Volta (1745 – 1827)
Kirchhoff’s Voltage Law(KVL)
▪ The voltage, or potential difference, btw two points in a circuit indicates the energy required to move charge from one point to the other.
13
Kirchhoff’s Voltage Law(KVL)
▪ The principle underlying KVL is that no energy is lost or created in an electric circuit; in circuit terms, the sum of all voltages associated with source must equal the sum of the load voltages, so that the net voltage around a closed circuit is _________?.

电路原理第二章.ppt

电路原理第二章.ppt

R11i1 R12i2 ... R1mim uS11 R21i1 R22i2 ... R2mim uS22 ........................
(2 25)
Rm1i1 Rm2i2 ... Rmmim uSmm 来自三、网孔分析法计算举例
网孔分析法的计算步骤如下： 1．在电路图上标明网孔电流及其参考方向。若全部网 孔电流均选为顺时针(或反时针)方向，则网孔方程的全部 互电阻项均取负号。 2．用观察电路图的方法直接列出各网孔方程。 3．求解网孔方程，得到各网孔电流。 4．假设支路电流的参考方向。根据支路电流与网孔电 流的线性组合关系，求得各支路电流。 5．用VCR方程，求得各支路电压。
写成一般形式：
G11v1 G12v2 G13v3 iS11
G21v1
G22v2
G23v3
iS22
G31v1 G32v2 G33v3 iS33
(2 29)
其中G11、 G22、G33称为节点自电导，它们分 别是各节点全部电导的总和。
G11v1 G12v2 G13v3 iS11
iSk ii i j
其中，当电流源(iSK)参考方向与网孔电流参考方向(ii或 ij)相同时取正号，相反则取负号。
例2－14 用网孔分析法求图2－24电路的支路电流。
图2－24
解：设电流源电压为u，考虑了电压u的网孔方程为：
补充方程
(1)i1 u 5V (2)i2 u 10V
i1 i2 7A
5A 10A
5 1
i1
10 2
3 1
A 5 A 1A 5
1 3
25
1 i2 2
10 A 15 A 3A
1
5
1 3

电路(英文版)第一章ppt课件


② If use Non-Passive sign convention, the relation will be minus；
③Indicate the resistor have no memory,and symmetrical at two terminal。 i R
Ohm’s law
u
+
Practise Calculate the power of every part.
Solve
i iS 2A
+
5V u
u 5V
P A iS u 2 5 10 W 2
P V uS i 5 (2) 10 W 5
-
release release
P（发）＝P（吸）
2. Fuel Cell(燃料电池）
电池电动势1.23V。以氢、氧作为燃料。约40-45%的化学能 转变为电能。实验阶段加燃料可继续工作。
氢氧燃料电池示意图
3. Solar Cell (太阳能电池）
一块太阳能电池电动势0.6V。太阳光照射到P-N结上， 形成一个从N区流向P区的电流。约 11%的光能转变为电 能，故常用太阳能电池板。 一个50cm2太阳能电池的电动势0.6V,电流0.1A
u
iS
0 i
例
Direct Current
+
u
iS
R
u RiS
u0
( R 0)
Resitor
u ( R )
Current source can’t be opend！
返 回
上 页
下 页
Actual Current soruce： 可由稳流电子设备产生，如晶体管的集电极 电流与负载无关；光电池在一定光线照射下光电 子被激发产生一定值的电流等。

电路分析英文课件ECTE170 Lecture 2

14
Example: Current Divider
• Find I1 of this circuit:
Determinethe totalresistanceR T first
42mA
6 24 R2
1 1 1 1 1 1 1 1 R T R1 R2 R3 6 24 24 4 24
R3
I1
R1
RT 4 RT 4 I1 I T 42m A 28m A R1 6
15
Current Sources
• A voltage source provides a constant output voltage, regardless of the load (i.e. resistance) connected to it
– Connecting batteries in parallel increases the current capacity, without usually changing the voltage provided at the terminals
4
Resistance in Parallel Circuits
16
Current Sources
• Similar to ideal voltage sources (which have no series resistance), an ideal current source has no parallel resistance • A real current source comprises an ideal current source, with a resistance (usually large) connected in parallel with it, as shown

电路原理英语知识点总结

电路原理英语知识点总结1. Electric Circuit ComponentsAn electric circuit is made up of various components that are necessary for the flow of electricity. The main components of an electric circuit include:- Voltage source: A voltage source provides the electrical energy required to initiate the flow of current in the circuit. Examples of voltage sources include batteries, generators, and power supplies.- Conductors: Conductors are materials that allow the flow of electrical current. They are usually made of copper or aluminum and are used to connect the various components of the circuit.- Resistors: Resistors are components that are used to control the flow of current in the circuit. They are made of materials that resist the flow of electricity and are used to limit the amount of current in a circuit.- Capacitors: Capacitors are components that are used to store and release electrical energy. They are made of plates separated by a dielectric material and are used to store charge in the circuit.- Inductors: Inductors are components that are used to store and release energy in the form of a magnetic field. They are made of coils of wire and are used in applications where energy storage is required.- Switches: Switches are components that are used to control the flow of current in the circuit. They can be used to open or close the circuit, allowing the flow of current to be controlled.2. Electric Circuit LawsThere are several laws and principles that govern the behavior of electric circuits. These laws are essential in understanding how electric circuits work and in analyzing and designing electrical systems. The main laws and principles of electric circuits include:- Ohm's Law: Ohm's law states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance. Mathematically, Ohm's law is expressed as I = V/R, where I is the current, V is the voltage, and R is the resistance.- Kirchhoff's Laws: Kirchhoff's laws are two principles that govern the behavior of electric circuits. Kirchhoff's current law states that the total current entering a junction is equal to the total current leaving the junction. Kirchhoff's voltage law states that the sum of the voltage drops around a closed loop in a circuit is equal to the sum of the voltage rises.- Thevenin's Theorem: Thevenin's theorem states that any linear electrical network can be replaced by an equivalent circuit consisting of a single voltage source and a single series resistor, where the voltage source is equal to the open-circuit voltage and the series resistor is equal to the Thevenin resistance.- Norton's Theorem: Norton's theorem is similar to Thevenin's theorem and states that any linear electrical network can be replaced by an equivalent circuit consisting of a single current source and a single parallel resistor, where the current source is equal to the short-circuit current and the parallel resistor is equal to the Norton resistance.- Maximum Power Transfer Theorem: The maximum power transfer theorem states that the maximum power is transferred from a source to a load when the load resistance is equal to the source resistance.3. Series and Parallel CircuitsElectric circuits can be connected in two ways: series and parallel. In a series circuit, the components are connected end-to-end, so that the current flows through each component in sequence. In a parallel circuit, the components are connected across each other, so that the current is divided and flows through each component simultaneously. Understanding the behavior of series and parallel circuits is important in the analysis and design of electrical systems.In a series circuit, the total resistance is the sum of the individual resistances, and the total voltage is the sum of the individual voltages. The current is the same in all components in a series circuit. In a parallel circuit, the total resistance is the reciprocal of the sum of the reciprocals of the individual resistances, and the total current is the sum of the individual currents. The voltage is the same across all components in a parallel circuit.4. Applications of Electric CircuitsElectric circuits have numerous applications in a wide range of electrical and electronics systems. Some of the key applications of electric circuits include:- Power distribution: Electric circuits are used to distribute electrical power from the source to the various loads in a system. Power distribution systems are essential in providing electricity to homes, industries, and other facilities.- Electronic devices: Electric circuits are used in the design and development of electronic devices, such as computers, smartphones, televisions, and other consumer electronics. The behavior of electric circuits is fundamental to the operation of these devices.- Control systems: Electric circuits are used in the design of control systems that are used to regulate and control the behavior of various systems. Control systems are used in industrial automation, robotics, and other applications.- Communication systems: Electric circuits are used in the design of communication systems, such as telecommunication networks, wireless communication systems, and satellite communication systems. These systems rely on the behavior of electric circuits to transmit and receive signals.- Renewable energy systems: Electric circuits are used in the design and implementation of renewable energy systems, such as solar power systems, wind power systems, and hydroelectric power systems. These systems rely on the behavior of electric circuits to convert and distribute the generated electrical energy.In conclusion, electric circuits are essential in the study and application of electrical engineering and technology. Understanding the principles of electric circuits, including their components, laws, behavior, and applications, is crucial in the design, analysis, and operation of electrical and electronics systems. Whether it is power distribution, electronic devices, control systems, communication systems, or renewable energy systems, electric circuits play a critical role in the functioning of modern electrical and electronic systems.。

电路原理课件


Electrical and Electronic Principles, WEI Yi
21
Thévenin to Norton conversion

To convert from the Thévenin equivalent circuit to the Norton equivalent circuit:
Circuits Analysis
Electrical and Electronic Principles, WEI Yi
7
Circuits Analysis: Preview
Current
I:
• Measured in amperes (A) • Analogous to volume flow rate (volume/unit time)
Electrical and Electronic Principles, WEI Yi 5
electronic devices
resistive touch screen
capacitive touch screen
6
Electrical and Electronic Principles, WEI Yi
Electrical and Electronic Principles, WEI Yi 8
A Simple DC Circuit
V V
Ohm’s law:
V IR
Electrical and Electronic Principles, WEI Yi 9
Voltage source
Ideal voltage source
Electrical and Electronic Principles, WEI Yi
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Alternative form of KCL:
The sum of the currents entering a node is equal to the sum of the currents leaving the node.
Case 2 (closed boundary)
Generalized: a node may be regarded as a closed surface shrunk to a point. Two dimension: a closed boundary is the same as a closed path.
In general
Potentiometer
Linear resistor: obey Ohm’s Law.
Slope R
Nonlinear resistor: does not obey Ohm’s Law.
Slope R
Conductance is the ability of an element to conduct
2.1 Introduction
To actually determine the values of these variables in a given circuit requires that we understand some fundamental laws that govern electric circuits. Basic Laws: Ohm’s Law Kirchhoff’s Law
KCL:
KCL states that the algebraic sum of currents entering a node (or a closed boundary) is zero.
i
n 1
N
n
0
Case 1 (node)
i1 i5 i4 i2 i3
i1 (i2 ) i3 i4 (i5 ) 0 or i1 i3 i4 i2 i5
i1 i2 (i3 ) (i4 ) (i5 ) 0 or i1 i2 i3 i4 i5
i1 i5
Closed Boundary
i4
i3 i2
Application of KCL
Series of current sources : a circuit cannot contain two different currents, I1 and I2, in series, unless I1= I2; otherwise, KCL will be violated Parallel of current sources: the combined current is the algebraic sum of the current supplied by the individual sources.
electric current, measured in siemens (S).
1 i G R v
Power representation of a resistor:
2 v p vi i 2 R R 2 i p vi v 2G G
Notice:
☺ The power dissipated in a resistor is a nonlinear function of either current or voltage
Passive sign convention:
i R
viR
If not conform with it:
v
v i R
Two extreme possible case:

Short Circuit: A short circuit is a circuit element with resistance approaching zero. v iR 0 Open Circuit: An open circuit is a circuit element with resistance approaching infinity v i lim 0 R R
☺ Since R and G are positive quantities, the power dissipated in a resistor is always positive. Thus, a resistor always absorbs power from the circuit. This confirms the idea that a resistor is a passive element, incapable of generating energy.
M
m
0
v1
v2

v3
Illustration
v4
v1 v2 v3 v4 v5 0 or v1 v2 v4 v3 v5
Alternative form of KVL:

v5

Sum of voltage drops = Sum of voltage rises
Application of KVL
Series of voltage sources : the combined voltage is the algebraic sum of the voltages of the individual sources. Parallel of voltage sources: a circuit cannot contain two different voltages, V1 and V2, in parallel, unless V1= V2; otherwise, KVL will be violated.
2.3 Nodes, Branches, and Loops
A Network is an interconnected of elements or devices. A circuit is a network providing one or more closed paths. In network topology, we study the properties relating to the placement of elements in the network and the geometric configuration of the network.

v2
3
20 V


v1
i

v2

3



Solution:
(a)
(b)
From Ohm’s Law, v1 2i, v2 3i (1) Applying KVL around the loop gives 20 v v 0 1 2 Substituting Eq.(1) into Eq.(2), there is
Nodes sents a single element such as a voltage source or a resistor. A Node is the point of connection between two or more branches. A Loop is any closed path in a circuit. (A loop is said to be independent if it contains a branch which is not in any other loop.)
(2)
20 2i 3i 0 i 4 A
Then
v1 8 V , v2 12 V
Example 2
Determine v0 and i in the following circuit.
i
4

2v0

4V
i
4

i
2v0

4V
12 V

12 V



6
v0 (a)
2.4 Kirchhoff’s Laws
KCL: Kirchhoff’s Current Law (based on the law of
conservation of charge)
KVL: Kirchhoff’s Voltage Law (based on the principle of
conservation of energy)
2.2 Ohm’s Laws
Resistance: the physical property (or ability) to resist current : resistivity l R where A : cross sec tional A l : length
Resistor:
Fixed: its resistance remains constant. (wire-wound type; carbon film type) Variable: variable resistors have adjustable resistance. (composition type; slider pot)
Resistor: the circuit element used to model the current-resisting behavior of a material (Simplest passive element)
Ohm’s Law:
Ohm’s Law states that the voltage v across a resistor is directly proportional to the current i flowing through the resistor