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Unformatted text preview: mcconnell (kam2342) – oldhomework 12 – Turner – (60230) 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 Why are thick wires rather than thin wires usually used to carry large current? 1. Thick wires have a larger heat capacity. 2. Thick wires are easier to make. 3. Thick wires have less resistance. correct 4. Thick wires are difficult to break. Explanation: Thick wires have less resistance and will more effectively carry currents without exces- sive heating. 002 10.0 points A resistor is made from a hollow cylinder of length l , inner radius a , and outer radius b . The region a < r < b is filled with material of resistivity ρ . Current runs along the axis of the cylinder. The resistance R of this component is 1. R = ρ ℓ π ( b 2- a 2 ) correct 2. R = π ( b 2- a 2 ) ρ ℓ 3. R = ρ ℓ b 2 π a 4 4. R = ρ a πℓ b 2 5. R = π b 2 ρ ℓ 6. R = 2 πρ ℓ ( b 2- a 2 ) 7. R = ρ ℓ a 2 π b 4 8. R = ρ ℓ π a 2 9. R = 2 ρ ℓ π b 2 10. R = ρ ℓ π b 2 Explanation: By definition R = ρ ℓ A = ρ ℓ π b 2- π a 2 = ρ ℓ π ( b 2- a 2 ) ....
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- Spring '10
- Superconductivity, Resistor, Correct Answer, Electrical resistance, Voltage drop