Final answer:
The average current in the lightbulb is 0.356 A. In 9.0 s, approximately 1.996 × 10^{19} electrons pass through the filament of the bulb.
Step-by-step explanation:
When a lightbulb is turned on and 6.40 C of charge pass through the filament of the bulb in 18.0 s, the average current (I) in the lightbulb can be calculated using the formula I = Q / t, where Q is the charge and t is the time. Thus, the average current is I = 6.40 C / 18.0 s = 0.356 A.
(b) To find how many electrons pass through the filament in 9.0 s, we first calculate the charge that flows in this time, which is half of the total charge since 9.0 s is half of 18.0 s. Therefore, in 9.0 s, 3.20 C of charge pass through the filament. The charge of one electron is approximately 1.602 × 10^{-19} C. The number of electrons n can be found by dividing the total charge by the charge of one electron: n = 3.20 C / (1.602 × 10^{-19} C/electron), resulting in n = 1.996 × 10^{19} electrons.