4. The resistivity "p" of a wire is expressed as p(x)=ax where a is a constant and x is thelength of the wire. Then calculate the ratio of R/R: if Ri and R:are the resistance values ofthe wires of resistivity p(x)=ax. The wires have lengths 2L and 3L respectively. (Assumethat the area of the wires are the same and constant.)

Answered: Image /qna-images/answer/87f62d52-4ebf-4d98-bd0c-ba223a492519.jpg

Answered: 4. The resistivity "p" of a wire is…

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter17: Current And Resistance

Section: Chapter Questions

Problem 21P

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Similar questions

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.
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.
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.
How does the resistance for copper and for silicon change with temperature? Why are the behaviors of these two materials different?
If two different wires having identical cross-sectional areas carry the same current, will the drift velocity be higher or lower in the better conductor? Explain in terms of the equation vd=1nqA by considering how the density of charge carriers n srelates to whether or not a material is a good conductor.
The current through a 12-gauge wire is given as I(t)=(5.00A)sin(260Hzt)). What is the current density at time 15.00 ms?

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