Drift Velocity

The drift velocity is given by: Where: - is the current, - is the number of charge carriers per unit volume, - is the cross-sectional area, - is the charge of an electron. When the length is doubled and the area is halved, the resistance of the wire will change. Since , doubling and halving will result in a fourfold increase in resistance. Since the current remains the same (as per the conservation of current), the drift velocity will be halved. Thus, the new drift velocity becomes .

Electron mobility , where is the drift velocity and is the electric field. Electric field , where is the potential difference and is the length of the wire. cm m V m V s V/m. m/s.