I = vAnq , Where:

- I = current (amps, A)
- v = drift velocity (m/s)
- A = cross-sectional area of the conductor (m2)
- n = charge density (m-3) This is the number of charge carriers that can move per m3
- q = charge on each charge carrier (coulombs, c)

**If the cross-sectional area of a wire is A and the number of charge carriers per m3 is n, then: **Number of charge carriers per metre of wire = An

**If each charge carrier is travelling at speed v (m/s) along the wire, then: **Number of charge carriers passing a point in the wire per second = vAn

**If each charge carrier has a charge q, then: **The amount of charge passing along the wire per second (i.e. the current, I) = vAnq

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