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Unformatted text preview: Reilly (mar3978) – homework 01 – Turner – (56725) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points At some automobile toll-collecting stations, a thin metal wire sticks up from the road and makes contact with cars before they reach the toll collector. What is the purpose of this wire? 1. To transfer positive particles to the auto- mobile 2. To transfer electrons to the automobile 3. To count the vehicles 4. To discharge the automobile correct 5. To warn the drivers Explanation: Metal wire can conduct net charges to the ground so that the car will discharge. 002 10.0 points The five thousand billion freely moving elec- trons in a penny repel one another. Why don’t they fly off the penny? 1. They are attracted to the five thou- sand billion positively charged protons in the atomic nuclei of atoms in the penny. correct 2. The electrons attract each other. 3. They don’t have enough speed. 4. They cause a jam when they try to fly away. 5. The shell of the penny prevents the elec- trons from flying. Explanation: The electrons are bound to the nuclei. 003 10.0 points How can a charged atom (an ion) attract a neutral atom? 1. An ion polarizes a nearby neutral atom, so that the part of the atom nearer to the ion acquires a charge opposite to the charge of the ion, and the part of the atom farther from the ion acquires a charge of the same sign as the ion. correct 2. The charged atom can emit x rays to induce ionization of the neutral atom. 3. The charged atom can hit the neutral atom and make it positively charged or nega- tively charged. 4. The charged atom can produce secondary electrons to interact with the neutral atom and make it positively charged or negatively charged. Explanation: An ion polarizes a nearby neutral atom, so that the part of the atom nearer to the ion acquires a charge opposite to the charge of the ion, and the part of the atom farther from the ion acquires a charge of the same sign as the ion....
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This note was uploaded on 11/30/2010 for the course PHY 60230 taught by Professor Turner,j during the Spring '10 term at University of Texas at Austin.
- Spring '10