Chapter 1-1 SI Units Voltage and Current basic circuit elements passive sign convention.

What this course is about Finding unknown Voltages and Currents Finding energy delivered or used Finding component values/configurations to create desired voltages and currents Learn fundamental definitions, rules and techniques Practice, practice…..and more practice

Problem Solving Approach Identify what’s given and what’s to be found Sketch a circuit diagram and/or modify existing diagram Decide on method or approach Solve it (may need to go back) Check to see if solution make sense!!!!!!

SI Units

Electric Voltage  

When we discuss or measure an electrical voltage we are looking at the potential difference between two points

Electric Current  

When we discuss or measure an electrical current we are looking at the charge flow through an element

Ideal Basic Circuit Element Has only two terminals Can be described mathematically in terms of current and/or voltage. Cannot be subdivided into other elements.

For circuit analysis we must assign a reference polarity for voltage and reference direction for current We will adopt the passive sign convention for this class Passive Sign convention: Whenever the reference direction for the current in an element is in the direction of the reference voltage drop across the element, use a positive sign in expressions relating the voltage to the current. Otherwise use a negative

Examples of passive sign convention

Examples of passive sign convention (Resistor)

SI Units related to Electrical Circuits What you should know SI Units related to Electrical Circuits Definitions Voltage and Current Definition of basic circuit element Be able to apply the passive sign convention 10 Future Technologies That May Change The World