TABLE 26.2 Resistivities and Temperature Coefficients of Resistivity for Various Materials Temperature Coefficient a [(°C)-'] Material Resistivitya (N • m) Silver 1.59 X 10-8 3.8 × 10-3 1.7 × 10-8 3.9 X 10-3 Соpper Gold 2.44 X 10-8 3.4 X 10-3 Aluminum 2.82 × 10-8 3.9 X 10-3 Tungsten 5.6 X 10-8 4.5 X 10-3 Iron 10 X 10-8 5.0 X 10-3 Platinum 11 X 10-8 3.92 X 10-3 Lead 22 X 10-8 3.9 X 10-3 1.00 X 10-6 3.5 X 10-5 Nichrome 0.4 X 10-3 Carbon -0.5 × 10-3 Germanium 0.46 -48 X 10-3 Silicond 2.3 × 103 1010 to 1014 -75 X 10-3 Glass Hard rubber 1013 Sulfur 1015 Quartz (fused) 75 X 1016 * All values at 20°C. All elements in this table are assumed to be free of impurities. b See Section 26.4. CA nickel-chromium alloy commonly used in heating elements. The resistivity of Nichrome varies with composition and ranges between 1.00 x 10-6 and 1.50 × 10-6N · m. d The resistivity of silicon is very sensitive to purity. The value can be changed by several orders of magnitude when it is doped with other atoms.

An aluminum wire with a diameter of 0.125 mm has a uniform electric field of 0.195 V/m imposed along its entire length. The temperature of the wire is 35.0°C. Assume one free electron per atom. (a) Use the information in this Table of Resistivities and Temperature Coefficients to determine the resistivity (in Ω · m) of aluminum at this temperature. (b) What is the current density (in MA/m2) in the wire? J =-----   MA/m2 (c) What is the total current (in mA) in the wire? I =---------  mA (d) What is the drift speed of the conduction electrons? vd =  ------µm/s (e) What potential difference must exist between the ends of a 1.70 m length of the wire to produce the stated electric field? ΔV = --------- V

When a potential difference of 112.8 V is applied between the ends of a 9.77 m long wire, the current density is 1.43 A/cm2. Calculate the conductivity of the wire material.

Problem 3: A 1.2 g wire has a density of 2.7 g/cm3 and a resistivity of 2.7 × 10−8 Ωm. The wire has a resistance of 15 Ω. a) How long is the wire? b) The wire is made up of atoms with valence 1 and molar mass 26.98 g/mol. What is the drift speed of the electrons when there is a voltage drop of 30 V across the wire?

A copper wire of radius a = 0.172 mm has an aluminum jacket of outer radius b = 0.231 mm. There is a current i = 1.58 A in the composite wire. Take the resistivity for copper and aluminum to be 1.69 × 10*Q-m and 2.75 × 10-°2-m. Calculate the current in (a) the copper and (b) the aluminum. (c) If a potential difference V = 10.4 V between the ends maintains the current, what is the length in meters of the composite wire? (a) Number i Units (b) Number i Units (c) Number i Units

A copper wire of radius a = 0.240 mm has an aluminum jacket of outer radius b = 0.329 mm. There is a current i = 1.57 A in the composite wire. Take the resistivity for copper and aluminum to be 1.69 × 10-8Ω·m and 2.75 × 10-8Ω·m. Calculate the current in (a) the copper and (b) the aluminum. (c) If a potential difference V = 13.1 V between the ends maintains the current, what is the length in meters of the composite wire?

An aluminum wire has a length of 1.50 m and a cross sectional area of 0.480 mm2. If the resistivity of aluminum is 2.82 ✕ 10−8 Ω · m and a potential difference of 0.900 V is maintained across its length, determine the current in the wire (in A).

A straight, cylindrical wire lying along the x axis has a length of 0.376 m and a diameter of 0.68 mm. It is made of a material described by Ohm's law with a resistivity of ρ = 4.86 ✕ 10−8Ω· m. Assume a potential of 4.143 V is maintained at the left end of the wire at x = 0. Also assume V = 0 at x = 0.376 m. Find the current density (in A/m2) in the wire.  Use scientific/exponential notation to represent your answer to this problem. Eg., -0.0001 can be written as 1.0e-4 or as 1.0E-4. Spaces are not allowed.

What is the current in a wire in which 3.62x1020 electrons pass a single point every 8.79 seconds? Report your answer with three significant digits. (e = 1.602x10-19 C)