ENGS2613 Intro Electrical Science Week 3 Dr. George Scheets Read 2.5, 3.1, & 3.2 Problems 2.17, 20, 22, 23, 26, & 27 Quiz #2, 3 February Analyze a circuit using either KVL or KCL equations Quiz #1 Available for pickup in ES016 Quiz 1A Scores have been bumped by 1 point Up to a max score of 10

Using Kirchhoff's Current Law Draw & label current thru every element Arbitrary direction Hit each circuit element once (& only once) Same current? Use same label Label voltage drops for each element Passive device (Resistor): MUST follow current directions Current into + voltage side, Current out on – voltage side Active device (Voltage or Current source): Generally Assume Current exits + side & enters – side Label voltages at each node Node = wire at single voltage. Boundary is set by any circuit element. Write Current Equations, mostly using KCL & Ohm's Law KCL: Sum of currents entering node = sum of currents exiting Solve Equations

DC Circuit with Resistors Pause. Look at circuit. Mark known voltages Mark known currents Is it possible to simplify? Worth doing so? Can you use Ohm's Law? Have 2 of 3 (V, I, or R)? Can you use KCL? Know I's thru a node, except one? Formally use KCL or KVL KCL: Write current equations based on Node Current I/O KVL: Write voltage add/drop equations (ΔV's) based on Current Loops

Noted Problem Areas Ohm's Law: V = IR KVL Loop Currents Power Voltage Drop across a device = Current thru the device * Device's Resistance Might Help to think of it as ΔV = IR KVL Loop Currents = Actual current thru a device if only 1 Loop Current More than one Loop Current? Actual current = sum of the Loop Currents Power Active device: P = VI Passive device (Resistor): P = VI = I2R = V2/R

Transistors Intel's i7 processor has over 1.3 billion transitors. Source: learn.mikroe.com & hothardware.com