Question

2. If 6x 10-17 electrons cross through an area per min, calculate the electric current If 10 A of current flows through a conductor, find the number of electrons passing per second.

Answer 1

Given:

(i) Number of electrons crossing through an area per minute is 6*10¹⁷

To find:

(i) Calculate the electric current

(ii) When 10 A current flows in the conductor, find the number of electrons passing per second.

Solution:

According to Coloumb's Law,

q = ne,

where q is the total charge of electrons,

n is the number of number of electrons (6*10¹⁷ )

e is the magnitude of charge on 1 electron (1.6*10⁻¹⁹ C)

So, total charge,

q = (6*10¹⁷)*(1.6*10⁻¹⁹) C

= 9.6*10⁻² C

Again, q = It

or, I = q/t

where

I is the total current

q is 9.6*10⁻² C

and, t is total time, 1 minute (60s)

Substituting the values, we get,

I = 9.6*10⁻²/60

= 1.6*10⁻³ A

This is the total current.

For the second part,

I = 10A

t = 1s

So, q = It

= (10*1) C

= 10C

Now, again, q = ne

⇒ n = q/e

= 10/(1.6*10⁻¹⁹)

= 6.25*10¹⁹

So, there are 6.25*10¹⁹ electrons present.