Table of contents

0. Math Review31m
- Math Review
  31m
1. Intro to Physics Units1h 29m
2. 1D Motion / Kinematics3h 56m
3. Vectors2h 43m
4. 2D Kinematics1h 42m
5. Projectile Motion3h 6m
6. Intro to Forces (Dynamics)3h 22m
7. Friction, Inclines, Systems2h 44m
8. Centripetal Forces & Gravitation7h 26m
9. Work & Energy1h 59m
10. Conservation of Energy2h 54m
11. Momentum & Impulse3h 40m
12. Rotational Kinematics2h 59m
13. Rotational Inertia & Energy7h 4m
14. Torque & Rotational Dynamics2h 5m
15. Rotational Equilibrium3h 39m
16. Angular Momentum3h 6m
17. Periodic Motion2h 9m
18. Waves & Sound3h 40m
19. Fluid Mechanics4h 27m
20. Heat and Temperature3h 7m
21. Kinetic Theory of Ideal Gases1h 50m
22. The First Law of Thermodynamics1h 26m
23. The Second Law of Thermodynamics3h 11m
24. Electric Force & Field; Gauss' Law3h 42m
25. Electric Potential1h 51m
26. Capacitors & Dielectrics2h 2m
27. Resistors & DC Circuits3h 8m
28. Magnetic Fields and Forces2h 23m
29. Sources of Magnetic Field2h 30m
30. Induction and Inductance3h 38m
31. Alternating Current2h 37m
32. Electromagnetic Waves2h 14m
33. Geometric Optics2h 57m
34. Wave Optics1h 15m
35. Special Relativity2h 10m

27. Resistors & DC Circuits

Microscopic View of Current

Physics

27. Resistors & DC Circuits

Microscopic View of Current

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Multiple Choice

What is the electron current in a gold wire with a radius of $1.5 mm$ when the electron drift speed is $1.0 \times 10^{- 4} m / s$ ?

1.0 \times 10^{19} s^{- 1}

2.3 \times 10^{19} s^{- 1}

3.1 \times 10^{19} s^{- 1}

3.8 \times 10^{19} s^{- 1}

4.2 \times 10^{19} s^{- 1}

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Verified step by step guidance

First, understand that the electron current (I) can be calculated using the formula I = n * A * v_d * e, where n is the number density of electrons, A is the cross-sectional area of the wire, v_d is the drift velocity, and e is the elementary charge.

Calculate the cross-sectional area (A) of the wire using the formula A = π * r^2, where r is the radius of the wire. Given that the radius is 1.5 mm, convert it to meters (1.5 mm = 0.0015 m) before substituting into the formula.

Determine the number density of electrons (n) for gold. This is typically given or can be found in a reference table. For gold, n is approximately 5.9 × 10^28 electrons/m^3.

Substitute the known values into the electron current formula: I = n * A * v_d * e. Use n = 5.9 × 10^28 electrons/m^3, A from step 2, v_d = 1.0 × 10^-4 m/s, and e = 1.6 × 10^-19 C (the charge of an electron).

Perform the multiplication to find the electron current. This will give you the electron current in terms of electrons per second, which can be compared to the given options to find the correct answer.