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**Unformatted text preview: **MasteringPhysics: Assignment Print View
A Few Bumps on the Road
Learning Goal: To learn to apply the microscopic theory of conduction. A gauge-12 wire has diameter centimeters and length meters. When the voltage volts is applied to the ends of the wire, the current is amperes. The concentration of free electrons in the wire is Part A Find the resistivity Hint A.1 of the wire. Hint not displayed Hint A.2 Hint not displayed Part A.3 Part not displayed Part A.4 Part not displayed Express your answer in ohm-meters. Use two significant figures. ANSWER: 2.7510 = -8 Part B Find the mean time Hint B.1 between electron collisions in the wire. Hint not displayed Hint B.2 Hint not displayed Hint B.3 Hint not displayed Express your answer in seconds. Use two significant figures. ANSWER: 2.2010 = -14 per cubic meter.
MasteringPhysics: Assignment Print View
Problem 28.1
1.50 electrons flow through a cross section of a 3.00 . iron wire in 6.00 .
The electron density of iron is Part A What is the electron drift speed? ANSWER: 41.6
Problem 28.6
Part A What is the surface charge density of a 1.0-mm-diameter wire with 1000 excess electrons per centimeter of length? ANSWER: -5.0910
-3
Problem 28.40
You need to design a 1.0 A fuse that "blows" if the current exceeds 1.0 A. The fuse material in your . stockroom melts at a current density of Part A What diameter wire of this material will do the job? ANSWER: 0.505 mm
Problem 28.41
MasteringPhysics: Assignment Print View
A 75.0 hollow copper cylinder is 90.0 long and has an inner diameter of 1.0 cm. The current . density along the length of the cylinder is 2105 Part A What is the current in the cylinder? ANSWER: 1.86 A
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