Question

The number of electrons presents in 1 coulomb of charge is:

1. 825 × 1016
2. 625 × 1016
3. 625 × 10-16
4. 6.25 × 1016

Answer 1

Correct Answer - Option 2 : 625 × 1016

Concept:

Electric Current (I):

• It is defined as the net amount of electric charge that flows through a cross-section of a conductor in an electric circuit in a per unit time.
• S.I unit of electric current is Ampere(A).

 

1 Coulomb (C):

• One Coulomb of charge is equal to the charge transported by an electric current of constant magnitude in one second of time.
• It is defined as the product of a 6.24 × 1018 ​charge of an electron.
• It is the S.I unit of electric charge.

Charge of one electron = 1.6 × 10-19 Coulomb.

Explanation:

We know that e = 1.6 × 10-19 C, i.e charge on the electron.

The total charge required is 1 Coulomb, q = 1C

Therefore we also know that q = n × e, (n = number of electrons on the charge)

Hence, n = q/e....(1)

Substituting all the values in the equation (1)

n = 1/1.6 × 10-19 ​= 625 × 1016

So, if 1A current flows through the conductor then 625 × 1016 electrons flow per second across the cross-section of the conductor.