Question

How many electrons constitute a current of one microampere?

• A. $6.25\times {10}^6$
• B. $6.25\times {10}^{12}$
• C. $6.25\times {10}^9$
• D. $6.25\times {10}^{15}$

Answer 1

The correct option is B $6.25\times {10}^{12}$

1 microampere=${10}^{-6}A={10}^{-6}C/s$

Hence, charge flowing per second=$q={10}^{-6}C$

Hence, number of electrons=$N=\frac{q}{e}=\frac{{10}^{-6}}{1.6\times {10}^{-19}}$

$⟹N=6.25\times {10}^{12}$

Answer-(B)