An electron moving in a wire collides again and again with atoms and travels an average distance between collisions that is called the man free path. If the mean free path is less in some metals, what can you say about the resistance of these metals? For a given conductor, what can you do to lengthen the mean free path? [2]

An electron moving in a wire collides again and again with atoms and travels an average distance between collisions that is called the man free path. If the mean free path is less in some metals, what can you say about the resistance of these metals? For a given conductor, what can you do to lengthen the mean free path? [2]

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter9: Current And Resistance

Section: Chapter Questions

Problem 46P: An electronic device designed to operate at any temperature in the range from 10.0C to 55.0C...

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An electron moving in a wire collides repeatedly with atoms and travels an average distance between collisions called the mean free path. If the mean free path is less in some metals, what can you say about the resistance of these metals? For a given conductor, what can be done to lengthen the mean free path?
Consider a resistor of resistivity 3.96 × 10-8 Ω • m. If an electric field of 12 V/m is applied across the resistor and the electron volume concetration in the conductor is 5.16 × 1028 per m3, determine the drift velocity, in mm/s, of the free electron constituting the current.
In a normal conductor heat is generated at a rate I 2R. Therefore a current-carrying conductor must dissipate heat effectively or it can melt or overheat the device in which it is used. Consider a long cylindrical copper wire (resistivity 1.72x 10-8 Ω*m) of diameter 0.75 mm. If the wire can dissipate 80 W/m2 along its surface, what is the maximum current this wire can carry?
In a conductor, electrons area. Free to move a macroscopic distance across the material b. Completely immobile c. Free to reposition themselves slightly to create a microscopicimbalance, but still bound to their original nucleus d. None of the above
Consider a conductor of length 69 millimeters and inner and outer diameters 7.98 millimeters and 13.77 millimeters, respectively. The charge carriers, as a group, travels end to end of the conductor in 4.68 seconds. If the electron volume concentration of the conductor is 7.00 × 1025 electrons per cubic meter, find the total current, in amperes, through the conductor.
A current of 5 A exists in a copper wire of length 50 m and diameter of 2.5 mm when applying apotential difference of 0.86 V. Assuming the current is uniform, calculate(a) the current density(b) electron drift speed.(c) the copper conductivity
A copper wire has a circular cross section with a radius of 1.25 mm. (a) If the wire carries a current of 3.70 A, find the drift speed of the electrons in this wire. (b) All other things being equal, what happens to the drift speed in wires made of metal having a larger number of conduction electrons per atom than copper? Explain.
Calculate the specific conductivity of the conductor in Mega(Ωm)-1 since the current passing through a conductor with a cross-section (1.00nm x 1.00µm), length of 10.00mm, is 1.00mA and the voltage value falling on it is 1.00V.
An electronic device designed to operate at any temperature in the range from 10.0C to 55.0C contains pure carbon resistors. By what factor does their resistance increase over this range?
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?
In which of the three semiconducting materials listed in Table 20.1 do impurities supply free charges? (Hint: Examine the range of resistivity for each and determine whether the pure semiconductor has the higher or lower conductivity.)
Suppose the current in a conductor decreases exponentially with time according to the equation I(t) = I0e-t/τ, where I0 is the initial current (at t = 0), and τ is a constant having dimensions of time. Consider a fixed observation point within the conductor. (Use the following as necessary: I0 and τ) (a) How much charge passes this point between t = 0 and t = τ? (If applicable, round any coefficients to 3 decimal places.)Q(τ) = (b) How much charge passes this point between t = 0 and t = 10τ? (If applicable, round any coefficients to 5 decimal places.)Q(10τ) = (c) How much charge passes this point between t = 0 and t = ∞? (If applicable, round any coefficients to 3 decimal places.)Q(∞) =