How To Calculate Drift Speed

Drift Speed Equation:

\[ v_d = \frac{i}{n \times q \times a} \]

Current (i):

Charge Carrier Density (n):

m⁻³

Charge (q):

Cross-sectional Area (a):

m²

Drift Speed (v_d):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Drift Speed?

Drift speed is the average velocity attained by charged particles, such as electrons, in a material due to an electric field. In electrical conductors, this drift speed is relatively slow compared to the speed of individual electron motion.

2. How Does the Calculator Work?

The calculator uses the drift speed equation:

\[ v_d = \frac{i}{n \times q \times a} \]

Where:

\( v_d \) — Drift speed (m/s)
\( i \) — Electric current (A)
\( n \) — Charge carrier density (m⁻³)
\( q \) — Charge of each charge carrier (C)
\( a \) — Cross-sectional area of the conductor (m²)

Explanation: The equation shows that drift speed is directly proportional to the current and inversely proportional to the charge carrier density, charge, and cross-sectional area.

3. Importance of Drift Speed Calculation

Details: Understanding drift speed helps in analyzing electrical conduction in materials, designing electronic components, and calculating current densities in various applications.

4. Using the Calculator

Tips: Enter current in amperes, charge carrier density in m⁻³, charge in coulombs, and cross-sectional area in m². All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is typical drift speed in copper wires?
A: Typically around 0.0001 m/s (0.1 mm/s) for 1 A current in 1 mm² copper wire.

Q2: Why is drift speed so slow compared to electric signal speed?
A: Electric signals travel at near light speed as electromagnetic waves, while drift speed is the actual movement of electrons.

Q3: How does temperature affect drift speed?
A: Higher temperature increases resistance (reducing current) but may also affect charge carrier density, making the relationship complex.

Q4: What's the difference between drift speed and Fermi velocity?
A: Fermi velocity is the speed of electrons at Fermi level (very fast), while drift speed is their net movement due to applied field (much slower).

Q5: Can drift speed be negative?
A: Yes, if current direction reverses, drift speed becomes negative indicating opposite direction of charge carrier movement.