Question

If one ampere of current flows through a conductor, then the number of electrons flowing across any cross-section of the conductor in 4 seconds is:
Charge on each electron is $1.6\times {10}^{-19}C$

• A. $2.5\times {10}^{18}$
• B. $2.5\times {10}^{19}$
• C. $2.5\times {10}^{20}$
• D. $1.6\times {10}^{18}$

Answer 1

The correct option is B $2.5\times {10}^{19}$

Electric current , I = $\frac{q}{t}$ =$\frac{n}{t}e$ ……(i)

q = total charge

n = number of electrons,

e = charge on each electron = $1.6\times {10}^{-19}C$.

t = 4 s, I = 1 A

So, from (i),

n = $\frac{I}{e}t$

$\Rightarrow$ n = $2.5\times {10}^{19}$