# Ohm’s law and Kirchhoff's laws

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Ohm’s law and Kirchhoff's laws
305221, Computer Electrical Circuit Analysis การวิเคราะห์วงจรไฟฟ้าทางคอมพิวเตอร์ 3(2-3-6) ณรงค์ชัย มุ่งแฝงกลาง คมกริช มาเที่ยง สัปดาห์ที่ 3 Ohm’s law and Kirchhoff's laws

Kirchhoff’s Current Law Kirchhoff’s Voltage Law
Outline 1 Objectives 2 Kirchhoff’s Current Law 3 Kirchhoff’s Voltage Law 4 Voltage & Current Division 5 Assignments

Objectives เพื่อให้นิสิตมีความรู้ความเข้าใจเกี่ยวกับ Kirchhoff’s current Law เพื่อให้นิสิตมีความรู้ความเข้าใจเกี่ยวกับ Kirchhoff’s Voltage Law เพื่อให้นิสิตมีความรู้ความเข้าใจเกี่ยวกับ Voltage และ Current Division

Branch Matthew Sadiku, define A branch represents a single element such as a voltage source or a resistor. William Hayt, define a branch as a single path in a network, composed of one simple element and the node at each end of that element.

Node Matthew Sadiku, a node is the point of connection between two or more branches. William Hayt, a point at which two or more elements have a common connection is called “a node”. =

Path & Loop William Hayt, The set of nodes and elements that we have passed through is defined as “a path”. Matthew Sadiku, A loop is any closed path in a circuit. William Hayt, If the node at which we started is the same as the node on which we ended, then the path is, by definition, a closed path or “a loop”.

Branches, Nodes, Path and Loops
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Kirchhoff’s Current Law Kirchhoff’s Voltage Law
Outline 1 Objectives 2 Kirchhoff’s Current Law 3 Kirchhoff’s Voltage Law 4 Voltage & Current Division 5 Assignments

Kirchhoff’s Current Law
Kirchhoff’s current law (KCL) states that “the algebraic sum of currents entering a node (or a closed boundary) is zero”.

KCL Example

Kirchhoff’s Current Law Kirchhoff’s Voltage Law
Outline 1 Objectives 2 Kirchhoff’s Current Law 3 Kirchhoff’s Voltage Law 4 Voltage & Current Division 5 Assignments

Kirchhoff’s Voltage Law
Kirchhoff’s voltage law (KVL) states “that the algebraic sum of all volt-ages around a closed path (or loop) is zero”.

Determine ix and vx ?

Determine ix and vx ?

Determine vR2 and v2 ?

Determine vx in the circuit ?

Determine vx in the circuit ?

Determine i and vo ?

Find currents and voltages in the circuit ?

Kirchhoff’s Current Law Kirchhoff’s Voltage Law
Outline 1 Objectives 2 Kirchhoff’s Current Law 3 Kirchhoff’s Voltage Law 4 Voltage Division 5 Assignments

Series Resistors and Voltage Division

Equivalent of Series Resistors
The equivalent resistance of any number of resistors connected in series is the sum of the individual resistances.

Voltage Division

Kirchhoff’s Current Law Kirchhoff’s Voltage Law
Outline 1 Objectives 2 Kirchhoff’s Current Law 3 Kirchhoff’s Voltage Law 4 Current Division 5 Assignments

Parallel Resistors The equivalent resistance of two parallel resistors is equal to the product of their resistances divided by their sum.

Equivalent Conductances
The equivalent conductance of resistors connected in parallel is the sum of their individual conductances.

Current Division

Kirchhoff’s Current Law Kirchhoff’s Voltage Law
Outline 1 Objectives 2 Kirchhoff’s Current Law 3 Kirchhoff’s Voltage Law 4 Voltage & Current Division 5 Assignments

Assignment # 1 In the circuit shown in Fig. 3.51, the resistor values are unknown, but the 2 V, source is known to be supplying a current of 7 A to the rest of the circuit. Calculate the current labeled i2.

Assignment # 2 The voltage source in the circuit of Fig has a current of 1 A flowing out of its positive terminal into resistor R1. Calculate the current labeled i2.

Assignment # 3 Referring to the circuit of Fig. 3.69, (a) determine the two currents i1 and i2; (b) compute the power absorbed by each element.

Assignment # 4 Determine a value for the voltage v as labeled in the circuit of Fig. 3.70, and compute the power supplied by the two current sources.

Assignment # 5 For the circuit presented in Fig. 3.75, determine the current labeled i by first combining the four sources into a single equivalent source.

Assignment # 6 Obtain v1 through v3 in the circuit of Fig

Assignment # 7 Find I and Vab in the circuit of Fig

Assignment # 8 Determine io in the circuit of Fig

Assignment # 9 Find Vx in the circuit of Fig

Assignment # 10 Find Vo in the circuit of Fig and the power dissipated by the controlled source.