Question

In electronic circuits it is not unusual to encounter currents in the microampere range. Assume a 36 μA current, due to the flow of electrons. Part A What is the average number of electrons per second that flow past a fixed reference cross section that is perpendicular to the direction of flow?

Answer 1

Answer:

n = 2.25 x 10¹⁴ electrons/s

Explanation:

The amount of electric current is defined as the electric charge passing through an area per unit time. Hence:

I = q/t

where,

I = Current

q = amount of charge

t = time interval

but,

q = ne

therefore,

I = ne/t

where,

n = no. of electrons

e = charge on single electron = 1.6 x 10⁻¹⁹ C

t = 1 s (for electrons passing per second)

I = Current = 36 μA = 3.6 x 10⁻⁵ A

Therefore,

3.6 x 10⁻⁵ A = n(1.6 x 10⁻¹⁹ C)/1 s

n = (3.6 x 10⁻⁵ A)/(1.6 x 10⁻¹⁹ C)

n = 2.25 x 10¹⁴ electrons/s