A copper wire has a cross sectional area of $1 m m^{2}$ . The electron density of copper is $8.5 \times 10^{28} m^{3}$ . Calculate the mean drift velocity of the electrons through the wire when the current is 3 A.

Q. Copper contains

8.4 \times 10^{28}

free electrons

/ m^{3}

. A copper wire of cross-sectional area

7.4 \times 10^{- 7} m^{2}

carries a current of

1

A. The electron drift speed is approximately.

Q. Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area

1.0 \times 10^{- 7} m^{2}

carrying a current of

1.5 A

. Assume the density of conduction electrons to be

9 \times 10^{28} m^{- 3}

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A copper wire of 3 mm2 cross sectional area carries a current of 5 ampere. The magnitude of the drifty velocity for the electrons in the wire, (Assume copper to be monovalent, MCu=63.5 kg/k mol and density of copper =8920 kg/m3).

The correct option is A 0.12 m/sGiven : A=3mm2=3×10−6 m2 I=5 A ρ=8920 kg/m3Number of free electron per unit volume ne=ρNAMCu∴ ne=8920×6.023×102363.5=8.46×1025 electrons m−3Drift velocity vd=IAnee∴ vd=53×10−6×8.46×1025×1.6×10−19=0.12 m/s

A copper wire of $3 m m^{2}$ cross sectional area carries a current of $5 a m p e r e$ . The magnitude of the drifty velocity for the electrons in the wire, (Assume copper to be monovalent, $M_{C u} = 63.5 k g / k m o l$ and density of copper $= 8920 k g / m^{3})$ .