0Drift Velocity
✅ Definition:
Drift velocity (vdv_dvd) is the average velocity of electrons in a conductor due to an applied electric field.
Even though electrons move randomly, an electric field gives them a small net motion along the wire.
Formula:
vd=IneAv_d = \frac{I}{n e A}vd=neAI
Where:
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III = current
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nnn = number density of electrons (electrons per m³)
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eee = charge of electron (1.6×10−191.6 \times 10^{-19}1.6×10−19 C)
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AAA = cross-sectional area of conductor
Key Points:
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Drift velocity is very small (~mm/s)
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But electrons are always moving randomly at high speed
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Explains why current flows instantly in a wire even though individual electrons move slowly
