In Fig. 24.17, a 100-mA current flows through a copper wire 0.10 mm in diameter, a salt solution in a 1.0-cm-diameter glass tube, and a vacuum tube where the current is carried by an electron beam 1.0 mm in diameter. The density of conduction electrons in copper is 1.1x10²⁹ m^-3. The current in the solution is carried equally by positive and negative ions with charges ?2e; the density of each ion species is 6.1x10²³ m^-3. The electron density in the beam is 2.2x10¹⁶ m^-3. Find the drift speed in each region.

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Vacuum tube 1.0 1.0 mm 0.10 mm Wire | Wire Solution Electron beam FIGURE 24.17 Problem 40