Consider theideal speed, that is, how electrons would move in the filament if the only force affecting their motion were that of the electric field generated by the battery.

The relevant circuit consisting of a battery, a switch, and an incandescent bulb (represented by an electrode) is illustrated in Figure 1 below. A close-up view of the electrode is shown in Figure 2 below. The tungsten filament is modeled as a straight wire connecting the two electrodes in the figures.

The light bulb filament is made out of tungsten. The following properties of tungsten may be useful to you in your calculations:

• The mass density of tunsten is?_m=19.3g/cm³.
• The atomic weight is M =183.8g/mol (gram per mole).
• A single tungsten atom provides two mobile electrons that can carry an electrical current.