1/30/08 Warm-up  Take out your homework and signed papers from last night to go over.

1/30/08 Objectives  Compare and contrast conductors and insulators.  Describe conventional current flow.  Trace conducting paths.  Describe effects of added resistors (parallel and series)

1/30/08 Today’s Plan  Review homework  Begin Week 1 Activities  Introduce CASTLE kits  Section 1 (not 1.9 or 1.10)  Section 2 (2.1, 2.2, 2.5, 2.9, 2.12, 2.13)  Homework: Week 1 assignments due Monday.

1/30/08 CASTLE  Capacitor aided system for teaching and learning electricity  Forget everything you know or THINK you know about electricity  Starts from the most basic concepts and builds a sound model.

1/30/08 Section 1  Requirements for the bulbs to light?  Do the bulbs light simultaneously?  Is there something happening in the wires?  How can you recognize a conductor?  What is the path of conduction in a light bulb?  Exercise 1.11

1/30/08 Symbology  Batteries  Wires  Resistors/bulbs  Capacitors

1/30/08 Circuit Diagrams  Draw diagram of circuit with 3 batteries and 2 bulbs.  Use arrow(s) to indicate the direction of conventional charge flow.

1/30/08 Section 2  2.1: 2 batteries and 1 round bulb. Test with compass needle deflection. Add a resistor to the circuit. What happens to the compass and the brightness of the bulb?  What does a resistor do in the circuit?

1/30/08  2.2: Replace resistor with bulb(s). Start with 1 round bulb. Then add single bulbs in the loop.  What happens to bulb brightness and compass deflection?  Are bulbs resistors?

1/30/08 Some Definitions  Conductors: charge freely flows  Insulators: resists flow of charge  Resistors: allow charge to flow, but at a lower rate than a conductor.  Resistance: degree that a material holds back charge.

1/30/08 Resistance  Measured in ohms ()  Color-coding of resistors  Material, size, and shape affect resistance  Which bulb has greater resistance? Examine filaments with hand lens.

1/30/08

Wires vs. Bulbs  How does the resistance of a wire compare to that of a bulb? (2.9)

1/30/08 Resistance Analogy  Straws and coffee stirrers.  Series vs. parallel straws (2.7, 2.10, 2.11)

1/30/08 Bulbs in Parallel  Figures 2.12a and 2.12b  What happens to charge flow when a bulb is added in parallel?  What is the relationship between charge flow (current) and resistance?

1/30/08 Capacitor  2 layers of conducting material separated by insulator  Capacitor plates  Terminals  Capacitance  Farad

1/30/08 Homework  Work on assigned problems and reading from chapters.