The electrical resistivity of copper (Cu) metal is po (T=20 °C) = 1.7 x 10* N•m at 20 °C. The temperature coefficient of electrical resistivity for Cu is, a = 390 x 10$ °C'. Calculate the temperature at which the magnitude of the electrical resistivity of Cu has increased by a factor of 2, when compared to its value at room temperature (20 °C). The temperature dependence of the resistivity is given by p(T) = po[1 + aAT]. A) Т - 154.8 °C В) т - 210 °С C) T= 276.4 °C D) T - 254.5 °C

The electrical resistivity of copper (Cu) metal is po (T=20 °C) = 1.7 x 10* N•m at 20 °C. The temperature coefficient of electrical resistivity for Cu is, a = 390 x 10$ °C'. Calculate the temperature at which the magnitude of the electrical resistivity of Cu has increased by a factor of 2, when compared to its value at room temperature (20 °C). The temperature dependence of the resistivity is given by p(T) = po[1 + aAT]. A) Т - 154.8 °C В) т - 210 °С C) T= 276.4 °C D) T - 254.5 °C

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter9: Current And Resistance

Section: Chapter Questions

Problem 17CQ: Resistors are commonly rated at 18W,14W,12W ,1 W and 2 W for use in electrical circuits. If a...

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Check Your Understanding Copper wires use routinely used for extension cords and house wiring for several reasons. Copper has the highest electrical conductivity rating, and therefore the lowest resistivity rating, of all nonprecious metals. Also important is the tensile strength, where the tensile strength is a measure of the force required to pull an object to the point where it breaks. The tensile strength of a material is the maximumamount of tensile stress it can take before breaking. Copper has a high tensile strength, 2108Nm2 A thirdimportant characteristic is ductility. Ductility is a measure of a material’s ability to be drawn into wires and a measure of the flexibility of the material, and copper has a high ductility. Summarizing, for a conductor to be a suitable candidate for making wire, there are at least three important characteristics: low resistivity, high tensile strength, and high ductility. What other materials are used for wiring and what are the advantages and disadvantages?
Resistors are commonly rated at 18W,14W,12W ,1 W and 2 W for use in electrical circuits. If a current of1 = 2.00 A is accidentally passed through a R=1.00 resistor rated at 1 W, what would be the most probable outcome? Is there anything that can be done to prevent such an accident?
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A nichrome rod of length LN = 78 cm is connected in series (end to end) to a carbon rod of length LC = 5 cm. Both rods have cross-sectional areas of A = 85 mm2. At T0 = 20° C the resistivity of nichrome is ρN = 1.50 × 10-6 Ω⋅m and the resistivity of carbon is ρC = 3.50 × 10-5 Ω⋅m. The temperature coefficient of nichrome is positive with a value αN = 0.4 × 10-3 °C-1. The temperature coefficient of carbon is negative with a value αC = -0.5 × 10-3 °C-1. The nonlinear dependence of the resistivity on temperature T can be written as ρ = ρ0eα(T-T0). A)Write an expression for the total resistance of the nichrome-carbon combination as a function of temperature in terms of quantities given in the introduction. Simplify your answer as much as possible. Answer to part A is r(t)= ( ( ρC LC )/A ) eαC ( T - T0 ) + ( ( ρN LN )/A ) eαN ( T - T0 ) B) Calculate the temperature in degrees Celsius for which the resistance of the carbon-nichrome combination will be a minimum. C) Calculate the…