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Drude model
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Electrons as a gas colliding with ions give Ohm's law.
σ = ne²τ/mTreats conduction electrons as a gas accelerated by the field and scattered after a mean time τ: σ = ne²τ/m, giving Ohm's law. It also explains the Wiedemann–Franz law approximately.
Copper τ ≈ 2.5×10⁻¹⁴ s.
Classical; correct treatment needs quantum mechanics.
In more detail
The Drude model treats conduction electrons in metals as a gas that collides with the lattice. It explains Ohm's law and resistivity using average collision times and drift.
Real-world uses
- Physicists use the Drude model to estimate conductivity of metals.
- It provides a simple picture for teaching electrical conduction.
- Physicists use the Drude model to estimate the conductivity of metals from electron collisions.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
What are the limits of the Drude model?
It fails for quantum effects, such as the heat capacity of metals, and needs quantum theory for accurate results.
What does it predict for resistivity?
Resistivity inversely proportional to electron density and collision time.
Is the Drude model accurate?
It explains Ohm's law and rough conductivity values, but it misses quantum effects needed for precise predictions.
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