Last Minute Lecture

Electric Current, Resistance & Circuits Explained | Chapter 25 of University Physics Chapter 25 transitions from static charges to moving charges, introducing how electric current flows, how materials resist that flow, and how circuits distribute and use electrical energy. You’ll learn the definitions and units of current and resistance, explore Ohm’s Law, understand how batteries and generators (emf sources) behave in real circuits, and see how microscopic conduction models underpin macroscopic circuit laws. Watch the full video summary here for detailed walkthroughs of circuit analysis and experimental demonstrations. Electric Current & Current Density Electric current ( I ) is the rate of charge flow: I = dQ/dt , with SI unit ampere (A) where 1 A = 1 C/s. Current direction is defined as the flow of positive charge. Current density ( J ) quantifies how current distributes over a conductor’s cross-sectional area: J = I/A , and relates microscopically via carrie...

Electrical Properties of Materials — Chapter 18 Summary from Callister’s Materials Science and Engineering Chapter 18 of Materials Science and Engineering by William D. Callister, Jr. and David G. Rethwisch examines how materials interact with electric fields and current, focusing on the principles of conductivity, semiconduction, and dielectric behavior. The ability to control and manipulate electrical properties is central to modern electronics, energy systems, and sensor technologies. Watch the full podcast-style summary below, and subscribe to Last Minute Lecture for comprehensive, chapter-by-chapter study guides to essential engineering textbooks! Understanding Electrical Conduction Ohm’s Law: The foundational relationship (V = IR) linking voltage, current, and resistance in materials. Types of Materials: Conductors: Metals with free electrons in partially filled energy bands, allowing high conductivity. Semiconductors: Materials (like ...