Question

A 60 W light bulb has a current of 0.5 A flowing through it. Calculate the number of electrons passing through a cross-section of the filament.
1. ≈ 3.1 × 10^-18 electrons / min
2. ≈ 3.1 × 10¹⁸ electrons / s
3. ≈ 3.1 × 10^-18 electrons / s
4. ≈ 3.1 × 10¹⁸ electrons / min

Answer 1

Correct Answer - Option 2 : ≈ 3.1 × 10¹⁸ electrons / s

Concept:

Electric current: It defined as the flow of electrons in a wire or rate of flow of charge in a conductor.

The formula for current is I = Q / t

Where Q = charge in Coloumb

t = time in second

Calculation:

Current carried by bulb(I) = 0.5 A

For t = 1 second

Q = I × t = 0.5 C

1 electron has a charge of 1.6 × 10^-19 C

For 0.5 C number of electrons passing through a cross-section of the filament is given as

= \(\frac{{0.5}}{{1.6 \times {{10}^{ - 19}}}} = 3.125 \times {10^{18}}\) electrons / s