Download presentation
Presentation is loading. Please wait.
1
Lecture 2 2.1 Sources 2.2 Ohm’s Law 2.4 Kirchhoff’s Laws
2
Voltage and Current Sources
3
Independent Sources
4
Characteristics An independent source establishes a voltage or current in a circuit without relying on voltages and currents elsewhere in the circuit. The value of the voltage or current supplied is specified by the value of the independent source alone.
5
Exercise
6
Dependent Sources
7
Characteristics Dependent sources establish a voltage or current whose value depends on the value of a voltage or current else where in the circuit. You cannot specify the value of a dependent source unless you know the value of the voltage or current on which it depends.
8
Exercise
9
What value of Vg is required for the wiring to be valid?
10
Ohm’s Law
11
Analogy The height of the water=voltage The volume of flow through the hole per second=current The smallness of the hole = resistance Water wheel hit by the flow from the hole = power
12
Thought Experiment #1 Fixed hole dimension↔ Fixed R Height of water↑ → flow rate↑. V↑ → I↑
13
Thought Experiment #2 Fixed height of water↔ Fixed V Hole dimension↑ → flow rate↑ R↓ → I↑
14
Derivation of Ohm’s Law Three variables: V,I and R. Different Possibilities: – V=IR (1) – I=VR (2) – R=VI (3) Intuition – If R is constant, V↑ → I↑. (3) is not possible. (1) and (2) are possible. – If V is constant, R↓ → I↑. (2) and (3) are not possible
15
Ohm’s Law V=IR Mnemonic: Victory Is Rare
16
Exercise Calculate the value v a Determine the power dissipated in the resistor
17
Exercise Calculate i d
18
Kirchhoff’s Laws
20
KCL Kirchhoff’s Current law (KCL) – The algebraic sum of all the currents at any node in a circuit equals zero
21
Exercise Sum the currents at each node
22
Multisim Demo
23
KVL Kirchhoff’s Voltage Law – The algebraic sum of all the voltage around any closed path in a circuit equals zero
24
Exercise Sum the voltages around each designated path in the circuit
25
Example 2.8 1.KCL at b 2.KVL around cabc loop 3.Solve for i o and i 1
26
Problem 2.18 1.KCL at the top node 2.KVL around the right loop 3.Find i 1, i 2, v o
27
Problem 2.21 Find i 1 if i 0 is 1A.
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.