Which of the following occurs in the conductors of the...

Name: Problem 75, Chapter 24: Essential University Physics Global Edition
Uploaded: 2020-05-15T12:46:13-08:00
Duration: 1 min 22 s
Channel: Mrinal Rana
Description: Which of the following occurs in the conductors of the preceding problem during the brownout? a. Both the electric field and electron drift speed decrease. b. The electric field decreases but the electron drift speed doesn't. c. The current is carried by fewer electrons. d. The electrons undergo more frequent collisions.

Which of the following occurs in the conductors of the preceding problem during the brownout? a. Both the electric field and electron drift speed decrease. b. The electric field decreases but the electron drift speed doesn't. c. The current is carried by fewer electrons. d. The electrons undergo more frequent collisions.

Which of the following occurs in the conductors of the preceding problem during the brownout?
a. Both the electric field and electron drift speed decrease.
b. The electric field decreases but the electron drift speed doesn't.
c. The current is carried by fewer electrons.
d. The electrons undergo more frequent collisions.

Key Concepts

Electric Field in Conductors

In a conductor, an electric field is established by an applied voltage that drives the motion of charge carriers (typically electrons). This field dictates the magnitude and direction of the force exerted on each electron, and a reduction in the applied voltage—as during a brownout—leads directly to a decrease in the internal electric field strength. This concept is central to understanding how electrical circuits respond when the supply voltage varies.

Electron Drift Velocity

Electron drift velocity is the average speed at which electrons move through a conductor when subjected to an electric field. According to the relationship v = ?E, where ? is the electron mobility and E is the electric field, a decrease in the electric field (as in a brownout) results in a reduction in drift velocity. This concept helps in linking microscopic charge motion with the observable current in the conductor.

Ohm’s Law and Microscopic Conduction

Ohm’s Law, which relates the current density in a conductor to the electric field through the conductivity (expressed as j = ?E), forms the basis for understanding electrical conduction on a microscopic level. It explains that as the electric field decreases, the resulting current also reduces because the drift velocity of the electrons, and hence the current density, is lower. This principle is key when analyzing how variations in applied voltage affect both the macroscopic current and the microscopic behavior of charge carriers.

Electron Collisions in Conductors

Electron collisions refer to the interactions between conduction electrons and the lattice ions, impurities, or phonons within a conductor. These collisions are responsible for electrical resistance and affect the overall drift velocity of electrons. While the frequency of collisions is a material property and is relatively independent of the applied field under normal conditions, their cumulative effect determines the net drift of electrons, especially when the driving electric field is weak, as during a brownout.

Brownout Effects on Electrical Conduction

A brownout is a condition where the supply voltage is reduced intentionally or due to network issues, leading to diminished electric fields within electrical devices and circuits. Understanding brownouts involves recognizing how a lower voltage results in a lower electric field, which in turn decreases the electron drift velocity and the current carried by the conductors. This concept is important in both practical power distribution and theoretical discussions of conduction phenomena.

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