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PHYSICS CONNECTION

Mean drift velocity is a motion quantity

Charge carriers have a small average motion through a conductor. That mean drift velocity determines how many carriers cross a section each second.

Distance drifted = vΔt I = nAev

Follow the reasoning

  1. Consider a conductor slice of length vΔt.
  2. Multiply its volume by carrier number density and charge per carrier.
  3. Divide the charge crossing the section by Δt to obtain current.
OFFICIAL OCR QUESTIONS

Try it in a past paper 1

Open the question, then use its mark scheme to check your work.

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Specification outcomes (3)
  • 3.1.1(a) Define and use displacement, instantaneous speed, average speed, velocity and acceleration.
  • 4.1.2(a) Define and understand mean drift velocity of charge carriers.
  • 4.1.2(b) Use and apply I = A n e v, where n is the number density of charge carriers.
Official OCR AS specification ↗