Question

A length of aluminum wire is connected to a precision 10.00-V power supply, and a current of 0.4212 A is precisely measured at 27.0 ∘C. The wire is placed in a new environment of unknown temperature where the measured current is 0.3804 A .

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For some applications, it is important that the value of a resistance not change with temperature. For example, suppose you made a 4.00 −kΩ−kΩ resistor from a carbon resistor and a Nichrome wire-wound resistor connected together so the total resistance is the sum of their separate resistances.

Part A

What value should each of these resistors have (at 0 ∘C∘C) so that the combination is temperature independent?

R0C=

Part B

RON

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A power station delivers 950 kWkW of power at 12,000 VV to a factory through wires with total resistance 5.0 ΩΩ .

How much less power is wasted if the electricity is delivered at 50,000 VV rather than 12,000 VV?

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The Tevatron accelerator at Fermilab (Illinois) is designed to carry an 18 mAmA beam of protons traveling at very nearly the speed of light (3.0×108 m/s)(3.0×108 m/s) around a ring 6300 mm in circumference.

How many protons are in the beam?

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A copper pipe has an inside diameter of 3.00 cmcm and an outside diameter of 5.00 cmcm (the figure (Figure 1)).

What is the resistance of a 14.5 mm length of this pipe?

Answer 1