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Unformatted text preview: terry (ect328) oldhomework 13 Turner (59130) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 3) 10.0 points The damage caused by electric shock depends on the current flowing through the body; 1 mA can be felt and 5 mA is painful. Above 15 mA, a person loses muscle control, and 70 mA can be fatal. A person with dry skin has a resistance from one arm to the other of about 1 . 1 10 5 . When skin is wet, the resistance drops to about 5400 . What is the minimum voltage placed across the arms that would produce a current that could be felt by a person with dry skin? Correct answer: 110 V. Explanation: Let : I min = 1 mA and R dry = 1 . 1 10 5 . The minimum voltage depends on the mini- mum current for a given resistance, so V min = I min R dry = (1 mA) parenleftbigg 1 A 1000 mA parenrightbigg (1 . 1 10 5 ) = 110 V . 002 (part 2 of 3) 10.0 points Using the same electric potential as in Part 1, what would be the current if the person had wet skin? Correct answer: 20 . 3704 mA. Explanation: Let : V min = 110 V and R wet = 5400 . For the voltage V from Part 1 and the resis- tance R wet , I = V min R wet = 110 V 5400 parenleftbigg 1000 mA 1 A parenrightbigg = 20 . 3704 mA ....
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This note was uploaded on 02/17/2010 for the course PHY 59130 taught by Professor Turner during the Fall '09 term at University of Texas at Austin.
- Fall '09