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Chap. 2 Circuit Elements. C ontents. 2.1 Voltage and Current Sources 2.2 Electrical Resistance (Ohm’s Law) 2.3 Construction of a Circuit Model 2.4 Kirchhoff’s Laws 2.5 Analysis of a Circuit Containing Dependent Sources. Objectives. 1. 了解 理想的基本電路元件的符號與特性 :獨立電壓與 - PowerPoint PPT Presentation
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Chap. 2 Circuit ElementsContents
2.1 Voltage and Current Sources2.2 Electrical Resistance (Ohm’s Law)2.3 Construction of a Circuit Model2.4 Kirchhoff’s Laws 2.5 Analysis of a Circuit Containing Dependent Sources
EX 2.4 Constructing a Circuit Model of a Flashlight
Short circuit
Open circuit
Switch
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EX 2.5 Construction of a Circuit Model Based on Terminal Measurements
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2.4 Kirchhoff’s Laws
Kirchhoff’s Current Law (KCL)
端點 (terminal): 電路元件的兩端 ; 節點 (node): 二個以上電路元件相連的地方
The algebraic sum of all the currents at any node in a circuit equals zero.(電路中任一節點其所有電流代數和為零 )
電流需有代表方向的代數符號,若將流出節點的電流定為正號,那麼流入節點就是負號。
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2.4 Contd. (KVL)
Kirchhoff’s Voltage Law (KVL)The algebraic sum of all the voltages around any closed path or loop in a circuit equals zero.(電路中任一封閉路徑或迴路其所有電壓代數和為零 )
封閉路徑或迴路 (closed path or loop) :指從某一節點開始,沿著選定的電路元件回到起點,且其間之節點只許經過一次。
若電壓下降為正號,那麼電壓上升就為負號;若電壓下降為負號,那麼電壓上升就為正號。
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EX 2.6 Using KCL
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EX 2.7 Using KVL
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EX 2.8 Applying Ohm’s Law and Kirchhoff’s Laws
(KCL)
(KVL & Ohm’s law)
Also,
(power supplied = power absorbed)Power Balanced
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EX 2.9 Constructing a Circuit Model Based on Terminal Measurements
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2.5 Analysis of a Circuit Containing Dependent Sources
◆ Once we know io , we can calculate vo using Ohm’s law. ◆ Once we know i , we also know the current of the dependent source 5 i. ◆ The current in the 500 V source is i.