Introduction to Electrical Computer Engineering Ohms Law Dr

Introduction to Electrical & Computer Engineering Ohm’s Law Dr. Cynthia Furse University of Utah 1

Ohm’s Law – Questions of the Day • What is Ohm's Law, and how do you apply it? • What are Resistance, Conductivity, – Resistivity? * What is resistance used for? 2

Find Currents & Voltages 3

Find Currents & Voltages 4

Resistance (R) and Resistivity (ρ) Resistance: ability to resist flow of electric current Resistance (R ) Ω (ohms) Resistivity (r) Ω/m (ohm-meters) -1 Conductivity (σ ) m/Ω Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Problem 2. 1: AWG-14 Cu wire R = 17. 1 ohms, T = 20 C. Find length. Resistance (R ) Ω (ohms) Resistivity (r) Ω/m (ohm-meters) Conductivity (σ ) m/Ω From Table 2 -2: AWG-14 d = 1. 6 mm A = π r 2 = π (1. 6 mm / 2) 2 All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher

Resistor Color Codes 1 k ohm 2. 4 kohm 4. 3 Mohm Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Water-Circuit Analogy Resistance (Rocks/Pipes) Voltage (Potential) Current (Flow) 9

How to Connect hoses in… Series Parallel 10

How is this applied to sea ice? 11