nagle_phys2020_fa07_lecture16 - Reading for last week:...

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1 1 • Reading for last week: Chapter 18 • Reading for this week: Review Chapter 18, Chapter 19.1-19.3 • CAPA #6 due on Friday • Topics for today: Resistivity, Power, Simple Circuits 2 Resistance R of a piece of conductor depends on 1) Composition or Material 2) Shape and Dimensions A = Area L = Length A L R ρ = Where ρ is resistivity – measure of internal friction; dependent on material composition. 3 Clicker Question 12 Two cylindrical resistors are made of the same material (same resistivity ρ ). Resistor 2 is twice as long and has twice the diameter of resistor 1. What is the ratio R 2 /R 1 ? A)2 B) 4 C) 1/2 D) 1/4 E) 1 Answer: 22 1 11 2 RL A 1 1 2 A 4 2 == × = (the resistivities cancel) 4 Resistivity map for silicon wafer 5 6 Mount the coil assembly on the ring stand with the clamp as shown. Connect it to the power supply and arrange the torch so that it will heat most of the coil when it is lit. Turn on the power supply and turn up the power very slowly, until the lamp glows brightly. Then light the burner and heat the iron wire until it glows red. The flashlight bulb will dim
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This note was uploaded on 02/27/2008 for the course PHYS 2020 taught by Professor Dubson during the Fall '06 term at Colorado.

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nagle_phys2020_fa07_lecture16 - Reading for last week:...

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