Series Circuits Explained: Ohm’s Law, Voltage Drop & Bad Connections

How does a bad connection affect a series circuit? In this video, I use a 46-year-old electronics kit to demonstrate Ohm’s Law, series-circuit rules, voltage drop, and what happens when unwanted resistance is added to a circuit. We’ll start with a simple resistor circuit and use actual voltage, resistance, and current measurements to see Ohm’s Law in action. Then we’ll switch to a light bulb so you can actually see what happens when additional resistance is introduced. That additional resistance can represent problems technicians encounter on vehicles, like corrosion, a poor connection, damaged wiring, or excessive resistance in a ground circuit. We’ll use voltage-drop testing to see where the source voltage is going and why the bulb becomes dim. We’ll also connect a DVOM in series as an ammeter to demonstrate one of the most important rules of a series circuit: current remains the same throughout the entire circuit. 🔧 ALLDATA DIY – Factory Repair Information Save 20% on any ALLDATA DIY subscription with promo code BTAT20: https://www.alldata.com/diy-us/en/fin... Affiliate link — I may earn a commission from qualifying purchases. 🌐 BILL TEACHES AUTOMOTIVE TECHNOLOGY Free automotive electrical calculators, circuit tools, practice activities, and more: https://billteachesauto.com 💬 JOIN THE BTAT DISCORD COMMUNITY Learning automotive electrical and diagnostics? Continue the conversation, ask questions, and learn with other technicians and students:   / discord   ⏱️ CHAPTERS 00:00 Introduction 03:19 Setting Up the 3-Volt Circuit 03:39 Ohm’s Law With a Resistor 04:14 Adding Resistance to the Circuit 05:13 Understanding Voltage Drop 07:05 Making It Visible With a Light Bulb 08:56 Simulating a Poor Connection 09:52 Finding the Voltage Drop 11:49 Calculating Total Circuit Resistance 14:08 Three Rules of a Series Circuit 16:03 Measuring Current With a DVOM 16:58 Proving Current Is the Same Everywhere 17:59 What’s Next: Parallel Circuits 🔧 TOOLS USED FOR DIAGNOSING ELECTRICAL ISSUES Kingbolen K7 scan tool: https://amzn.to/4hRc4lM Test Light for Simple and reliable circuit testing: https://amzn.to/47CMjQ7 Digital Multimeter for Voltage drop and circuit testing: https://amzn.to/4tDNhoG Automotive Jumper Wire Kit: https://amzn.to/4ru9u7n Power Probe for Quick power and ground testing: https://amzn.to/4kJohbA 🔧 ELECTRICAL DIAGNOSTIC TOOLS I RECOMMEND Back Probe Kit For testing connectors without damage: https://amzn.to/3P2NmCD Terminal Removal Tool Kit: https://amzn.to/4uruoG8 Heat Shrink Connector Kit: https://amzn.to/40IsPpH Fuse Assortment Kit: https://amzn.to/4cBxvEV Wire Stripper / Crimper: https://amzn.to/3Nh32BI Battery Tester: https://amzn.to/47d7E2H As an Amazon Associate, I earn from qualifying purchases. Using these links helps support Bill Teaches Automotive Technology at no additional cost to you. 📖 TOOLBOX TRUTHS Toolbox Truths: A 365-Day Devotional Guide for Automotive Technicians & Tradesmen Written specifically for mechanics and serious tradesmen. https://amzn.to/4qUxmQc If this video helped you better understand series circuits and automotive electrical diagnosis, consider subscribing to Bill Teaches Automotive Technology. A future video will cover parallel circuits and show how they behave very differently from the series circuit we tested here. #AutomotiveElectrical #SeriesCircuits #OhmsLaw