1. PHYS 221 Recitation Kevin Ralphs Week 1

2. Introduction TA: Kevin Ralphs – Email: kralphs@purdue.edukralphs@purdue.edu – Web Site: http://web.ics.purdue.edu/~kralphshttp://web.ics.purdue.edu/~kralphs – Office: PHYS 137 – Office Hours: Email to request – Help Center Hours: M 9:00-11:00, 2:00-3:30 Th 1:30-3:30

3. 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

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

5. 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

6. Coulomb’s Law

7. Principle of Superposition

8. 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,

9. Electric Field