Question

A current of 6mA is passing through a wire. How many electrons are passing in 15 min through cross section of wire

Answer 1

I = 6 mA = 6/1000 A
Time = 15 min = 15*60= 900 sec

Q = I *T
Q = 6*900/1000
Q = 54/10
Q = 5.4 coulomb

No. Of electrons = Q *6*10^18
= 5.4 * 6 *10^18
= 32.4 * 10^18
= 3.24 * 10^19

Answer 2

3.5 × 10¹⁹ electrons are passing through the cross-section of the wire in 15 minutes.

Given:

Current in the wire (i) = 6 mA

Time (t) = 15 minutes

To Find:

The number of electrons passing through the cross-section of wire in 15 minutes.

Given:

Let the number of electrons passing through the cross-section of the wire in 15 minutes be n.

Let the total charge flowing through the cross-section of the wire be Q.

• Time (t) = 15 × 60 = 900 seconds

• Current (i) = 6 mA = 6 × 10⁻³ A

→ The current is defined as the rate of flow of charge. Current is the amount of charge passing through the conductor in unit time.

                             $\therefore Current(i)=\frac{Charge(Q)}{Time(t)}\\\\\therefore Charge(Q)=(Current)(Time)$

→ Hence the total charge flowing (Q) will be equal to the product of Current (i) and Total time (t).

                           $\therefore Q=it=(6)(10^{-3} )(900)=5.4 C$

∴ Total charge flowing (Q) = 5.4 Coulomb

→ Charge on one electron (e) = 1.6 × 10⁻¹⁹ Coulomb

∴ Charge on 'n' electrons (Q) = n × e

                                           ∴ Q = n × e

                                         → 5.4 = n × (1.6 × 10⁻¹⁹)

                                         → 3.5 = n × 10⁻¹⁹

                                       ∴ n = 3.5 × 10¹⁹ electrons

Hence, 3.5 × 10¹⁹ electrons are passing through the cross-section of the wire in 15 minutes.

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