If the charge on an electron is $$1.6 \times 10^{-19}$$ coulombs , how many electrons should pass through a conductor in $$1$$ second to constitute $$1$$ ampere current ?
We know that
$$I = \dfrac {Q}{t}$$
$$\Rightarrow 1 \,A = \dfrac {Q}{1 \,s}$$
$$\Rightarrow Q = 1 \,C$$
Now, charge of one electron is $$1.6 \times 10^{-19}$$ coulombs
Therefore, in $$1$$ coulomb charge, number of electrons $$=$$$$\dfrac {1}{1.6 \times 10^{-19}} = 0.625 \times 10^{19} $$
$$= 6.25 \times 10^{18}$$ electrons