1. PHY 2049: Physics II Tutoring Center is open in room NPB 1215, M-F 12:00AM -4:00PM. It is free.

2. HITT 1 You buy a “75W” light bulb. The label means that: A. no matter how you use the bulb, the power will be 75W B. the bulb was filled with 75W at the factory C. the actual power dissipated will be much higher than 75W since most of the power appears as heat D. the bulb is expected to burn out after you use up its 75W E. none of the above

3. Currents Sample problem 26-2. A. 1.9 A B. 7.1 A

4. Resistances R = ρl/A Rank them by current, lowest first.

5. Superconductors Resistance is zero –transmission losses, switches Magnetic field is expelled -levitation Small thermal conductivity - thermal switches SQUID - low fields and low voltages

6. Circuits, Junctions Charge can not be created, nor destroyed Total Current in = Total current out i = 8A - 

7. Resistances n circuit in series R = R 1 + R 2 In parallel 1/R = 1/R 1 + 1/R 2

8. Work and emf Pumping of charges Potential difference around a loop adds to zero

9. Resistances Each of the resistors in the diagram has a resistance of 12 Ω. The resistance of the entire circuit is

10. More Resistance in parallel A coaxial cable consists of a wire of material A, resistivity ρ A radius R 1, surrounded by a shell of another material B with resistivity ρ B. The total radius is R 2. What is its resistance (per unit length)?

11. HITT2 A total resistance of 3.0 Ω is to be produced by combining an unknown resistor R with a 12 Ω resistor. What is the value of R and how is it to be connected to the 12 Ω resistor? A. 4.0 Ω, parallel B. 4.0 Ω, series C. 2.4 Ω, parallel D. 2.4 Ω, series E. 9.0 Ω, series