Question

When a steady current of $1A$ flows through a copper wire, the number of electrons crossing any cross-section area of the wire in one second is ______.

• A. $6.25\times {10}^{16}$
• B. $6.25\times {10}^{18}$
• C. $625\times {10}^{18}$
• D. $6.25\times {10}^{20}$

Answer 1

Answer: (B)

$6.25\times {10}^{18}$

Charge $Q=It=1A\times 1s=1C$

Now, $Q=Ne$ where N=number of electrons

$N=\frac{Q}{e}=\frac{1}{1.6\times {10}^{-19}}$

$⟹N=6.25\times {10}^{18}$

Answer-(B)