solution3_pdf - white (rw22679) Hw03 Ross (10219) 1 This...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: white (rw22679) Hw03 Ross (10219) 1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Birds resting on high-voltage power lines are a common sight. The copper wire on which a bird stands is 1 . 34 cm in diameter and carries a current of 95 A. Coppers resistivity is 1 . 68 10- 8 m . If the birds feet are 1 . 76 cm apart, what is the potential difference across its body? Correct answer: 199 . 18 V. Explanation: Let : r = 0 . 67 cm = 0 . 0067 m , I = 95 A , L = 1 . 76 cm = 0 . 0176 m , and = 1 . 68 10- 8 m . The resistance of the wire between the feet is R = L A so the potential is V = I R = I L A = (95 A) (1 . 68 10- 8 m) (0 . 0176 m) (0 . 0067 m) 2 10 6 V V = 199 . 18 V . 002 10.0 points A 17 V battery delivers 119 mA of current when connected to a 72 resistor. Determine the internal resistance of the battery. Correct answer: 70 . 8571 . Explanation: Let : V = 17 V , I = 119 mA = 0 . 119 A , and R = 72 . The internal resistance is in series with the given resistor, so V = I ( R + r ) r = V I- R = 17 V . 119 A- 72 = 70 . 8571 . 003 (part 1 of 2) 10.0 points A transistor radio operates by means of a 12 V battery that supplies it with 56 mA current. If the cost of the battery is 2 . 01 dollars and it lasts for 317 h, what is the cost per kWh to operate the radio in this manner? Correct answer: 9 . 43556 dollars / kW h. Explanation: Let : V = 12 V , I = 56 mA , c 1 = 2 . 01 dollars , and t = 317 h . The energy is E = P t = ( I V ) t , so the cost per kilowatt hour is c u 1 = c 1 E = c 1 I V t = 2 . 01 dollars (56 mA) (12 V) (317 h) parenleftbigg 1000 mA 1 A parenrightbiggparenleftbigg 1000 W 1 kW parenrightbigg = 9 . 43556 dollars / kW h white (rw22679) Hw03 Ross (10219) 2 004 (part 2 of 2) 10.0 points(part 2 of 2) 10....
View Full Document

This note was uploaded on 12/01/2010 for the course PHYSICS 21900 taught by Professor Rhoads during the Spring '10 term at IUPUI.

Page1 / 6

solution3_pdf - white (rw22679) Hw03 Ross (10219) 1 This...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online