PHYS 221 Recitation Kevin Ralphs Week 1

Introduction TA: Kevin Ralphs – – Web Site: – Office: PHYS 137 – Office Hours: to request – Help Center Hours: M 9:00-11:00, 2:00-3:30 Th 1:30-3:30

Preliminaries Recitations will largely focus on a conceptual approach to the material Memorization of equations and constants will not help you on the exam Understanding the concepts sometimes allows you to almost instantly answer a question

Useful Math Working with Vectors Solving Systems of Equations Varying Quantities in an Equation

Coulomb’s Law What does it tell me? – It tells you the force between two charged particles Why do I care? – Forces describe the acceleration a body undergoes – The actual path the body takes in time can be found from the acceleration using kinematic equations

Coulomb’s Law

Principle of Superposition

Electric Field What does it tell me? – The force a positive test charge would experience at a point in space Why do I care? – Calculating the force a particular charge feels doesn’t directly tell you how other charges would behave – The electric field gives you a solution that applies to any charge, so it reduces your work – Philosophically,

Electric Field