Question : A conductor material has a free-electron density of 1024 electrons per metre3. When a voltage is applied, a constant drift velocity of 1.5 × 10−2 metre/second is attained by the electrons. If the cross-sectional area of the material is 1 cm2, calculate the magnitude of the current.
Electronic charge is 1.6 × 10−19 coulomb
Solution. The magnitude of the current is
i = nAeν amperes
Here, n = 1024 ;
A = 1 cm2 = 10−4 m2
e = 1.6 × 10−19 C ;
v = 1.5 × 10−2 m/s
∴ i = 1024 × 10−4 × 1.6 × 10−19 × 1.5 × 10−2
= 0.24 A
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