2. A cylindrical metal rod is 1.90 m long and 5.50 mm in diameter. The resistance between its two ends is 1.09 x10 -3 2. (a) What is the resistivity of the material? (b) A round disk, 2.00 cm in diameter and 1.00 mm thick, is formed of the same material. What is the resistance between the round faces, assuming that each face is an equipotential surface?

2. A cylindrical metal rod is 1.90 m long and 5.50 mm in diameter. The resistance between its two ends is 1.09 x10 -3 2. (a) What is the resistivity of the material? (b) A round disk, 2.00 cm in diameter and 1.00 mm thick, is formed of the same material. What is the resistance between the round faces, assuming that each face is an equipotential surface?

Physics for Scientists and Engineers, Technology Update (No access codes included)

9th Edition

ISBN:9781305116399

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter27: Current And Resistance

Section: Chapter Questions

Problem 27.75AP: Review. When a straight wire is warmed, its resistance is given by R = R0,[1 + a(T T0)] according...

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When a straight wire is heated, its resistance changes according to the equation R = R0 [1 + (T T0)] (Eq. 17.7), where is the temperature coefficient of resistivity. (a) Show that a more precise result, which includes the length and area of a wire change when it is heated, is R=R0[1+(TT0)][1+(TT0)][1+2(TT0)] where is the coefficient of linear expansion. (See Topic 10.) (b) Compare the two results for a 2.00-m-long copper wire of radius 0.100 mm, starting at 20.0C and heated to 100.0C.
Two conducting wires A and B of the same length and radius are connected across the same potential difference. Conductor A has twice the resistivity of conductor B. What is the ratio of the power delivered to A to the power delivered to B? (a) 2 (b) 2 (c) 1 (d) 12 (e)12
Review. When a straight wire is warmed, its resistance is given by R = R0,[1 + a(T T0)] according to Equation 27.20, where a is the temperature coefficient of resistivity. This expression needs to be modified if we include the change in dimensions of the wire due to thermal expansion. For a copper wire of radius 0.100 0 mm and length 2.000 m, find its resistance at 100.0C, including the effects of both thermal expansion and temperature variation of resistivity. Assume the coefficients are known to four significant figures.
Explain why R=R0(1 + a?T) for the temperature variation of the resistance R of an object is not as accurate as P=P0(1 + a?T) which gives the temperature variation of resistivity P.
67. A straight, cylindrical wire lying along the x axis has a length of 0.500 m and a diameter of 0.200 mm. It is made of a material described by Ohm’s law with a resistivity of r 5 4.00 3 1028 V ? m. Assume a poten- tial of 4.00 V is maintained at the left end of the wire at x 5 0. Also assume V 5 0 at x 5 0.500 m. Find (a) the magnitude and direction of the electric field in the wire, (b) the resistance of the wire, (c) the magnitude and direction of the electric current in the wire, and (d) the current density in the wire. (e) Show that E 5 rJ.
25.69 A 1.50-m cylinder of radius 1.10 cm is made of a complicated mixture of materials. Its resistivity depends on the distance x from the left end and obeys the formula rho(x) = a + bx2, where a and b are constants. At the left end, the resistivity is 2.25 X 10-8 Ohm-meters, while at the right end it is 8.50 X 10-8 Ohm-meters. (a) What is the resistance of this rod? (b) What is the electric field at its midpoint if it carries a 1.75-A current?
A cylindrical metal rod is 1.60 m long and 5.50 mm in diameter. The resistance between its two ends (at 20°C) is 1.09 * 10-3 ohm. (a) What is the material? (b) A round disk, 2.00 cm in diameter and 1.00 mm thick, is formed of the same material.What is the resistance between the round faces, assuming that each face is an equipotential surface?
What current flows through a 2.54-cm-diameter rod of pure silicon that is 20.0 cm long, when 1.00 X 103 V is applied to it? (Such a rod may be used to make nuclear-particle detectors, for example.)
The given problem concerns a high-voltage transmission line. Such lines are made of bare wire; they are not insulated. Assume that the wire is 100 km long, has a resistance of 7.0 Ω, and carries 200 A. A bird is perched on the wire with its feet 2.0 cm apart. What is the potential difference between its feet?
Consider two coaxial conducting spheres of radii a and b = 2a. Filled with a conductive material with resistivity p = p0 (1 + r / a) between the radii (region a≤r≤b). Calculate the resistance between the spheres.
1. An isolated parallel-plate capacitor has an inital capacitance of 400nF and a charge of 5uC. Find the potential energy if the stored charge is doubled. A. - 125uJ B. 125uJ C. 93.8uJ D. 31.3uJ 2. With the following statements regarding resistivity and conductivity of a thing, which is/are ALWAYS TRUE? I. Resistivity of a thing is temperature-dependent. II. Conductivity of a thing is temperature-dependent. III. When resistivity of a material increases, then there is a decrease in conductivity. Please answer both question for a 100% rating.
25.21 A current-carrying gold wire has diameter 0.84 mm. The electric field in the wire is 0.49 V/m. What are (a) the current carried by the wire; (b) the potential difference between two points in the wire 6.4 m apart; (c) the resistance of a 6.4-m length of this wire?