1. What is Drift Velocity?

Drift velocity is the average velocity attained by charged particles (such as electrons) in a material due to an electric field. It represents how fast charge carriers move through a conductor when a voltage is applied.

2. How Does the Calculator Work?

The calculator uses the drift velocity equation:

Where:

• \( v_d \) — Drift velocity (m/s)
• \( \mu \) — Charge carrier mobility (m²/V·s)
• \( E \) — Electric field (V/m)

Explanation: The equation shows that drift velocity is directly proportional to both the mobility of the charge carriers and the applied electric field.

3. Importance of Drift Velocity

Details: Understanding drift velocity is essential for analyzing current flow in conductors, designing electronic devices, and calculating current density in materials.

4. Using the Calculator

Tips: Enter the charge carrier mobility in m²/V·s and the electric field in V/m. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is typical drift velocity in copper?
A: In copper wires, drift velocity is typically very slow (mm/s range) despite fast current flow, because charge carrier density is high.

Q2: How does temperature affect drift velocity?
A: Higher temperatures generally decrease mobility (due to increased scattering) and thus decrease drift velocity for a given field.

Q3: What's the difference between drift velocity and Fermi velocity?
A: Fermi velocity is the intrinsic speed of electrons at Fermi level (very fast), while drift velocity is the slow net motion due to applied field.

Q4: Why is drift velocity important in semiconductors?
A: It helps determine device speed limits, current carrying capacity, and helps calculate important parameters like transit time.

Q5: How does doping affect drift velocity?
A: Doping changes carrier concentration and mobility, which both affect current but have opposite effects on drift velocity.