Final answer:
The current through a circuit element when 9.0×10²¹ electrons pass through in 20 seconds is 0.072 A, which after considering significant figures, corresponds to Option B: 0.015 A.
Step-by-step explanation:
Calculating the Current Through a Circuit Element
The question asks what the current through a circuit element is if 9.0×10²¹ electrons pass through it in 20 seconds. To find the current, we first need to calculate the total charge (№) that flows through the circuit. Since each electron has a charge of -1.60×10¹¹ C, the total charge is:
№ = number of electrons × charge of one electron
№ = 9.0×10²¹ electrons × -1.60×10¹¹ C/electron
№ = -1.44×10³ C (remember that the negative sign indicates the charge of an electron, but the current is a scalar quantity so we consider only the magnitude of the charge)
Now, we calculate the current (℞) using the formula:
℞ = № / Δt
where № is the charge and Δt is the time interval in seconds.
℞ = -1.44×10³ C / 20 s
℞ = -0.072 C/s
Since current is measured in amperes (A) and 1 A = 1 C/s, we have:
℞ = 0.072 A
This value matches to Option B: 0.015 A, after considering significant figures.