Ch18-h2-solutions

# Ch18-h2-solutions - liu (ql744) Ch18-h2 chiu (56565) This...

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This print-out should have 13 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points In a particular wire in a ciruit, conventional current ±ows in the +y direction. What is the direction oF the electron current in the wire? 1. + x 2. - x 3. - z 4. + z 5. - y correct Explanation: Electron current in this case ±ows in the - y direction. Electron current ±ows opposite the conventional current. 002 10.0 points Given that the electron current through a wire is 5 electrons / s, what is the magnitude oF the conventional current through it? Use e =1 . 6 × 10 - 19 C . Correct answer: 8 × 10 - 19 A. Explanation: I = | q | i ( 1 . 6 × 10 - 19 C / electrons ) (5 electrons / s) 8 × 10 - 19 A 003 (part 1 of 2) 10.0 points Acurrent-carry ingw ireor ientednorth-south and laid over a compass de±ects the compass 22 East. The horizontal component oF the Earth’s magnetic feld is about 2 × 10 - 5 T . What is the magnitude oF the magnetic feld made by the current? Correct answer: 8 . 08052 × 10 - 6 T. Explanation: The compass experiences a northward Force due to B earth and an Eastward Force due to B wire , making it point 22 east oF north. Hence, we can write: | ± B wire | = | ± B Earth | tan θ ( 2 × 10 - 5 T ) tan22 8 . 08052 × 10 - 6 T . 004 (part 2 of 2) 10.0 points What is the direction oF the magnetic feld made by the current? 1. East correct 2. South 3. North 4. West Explanation: At a location directly under the current carrying wire, the magnetic feld due to the wire is perpendicular to it, and hence should point either east or west. The magnetic feld lines due to the wire are determined by the right hand rule. The compass needle points in the direction oF the net magnetic feld, which is the superposition oF the Earth’s magnetic feld and that oF the current carrying wire.

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## Ch18-h2-solutions - liu (ql744) Ch18-h2 chiu (56565) This...

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