A wire of diameter 0.02 m contains 1028 free electrons per cubic metre. An electrical current of 100 flows through the wire. The drift velocity of the free electrons in the wires is nearly

Question

A wire of diameter 0.02 m contains 1028 free electrons per cubic metre. An electrical current of 100 flows through the wire. The drift velocity of the free electrons in the wires is nearly (A) 10-19 m / s (B) 5 × 10-10 m / s (C) 2 × 10-4 m / s (D) 8 × 103 m / s

Tardigrade Admin · Accepted Answer

By using Vd=(I/n e A) =(100/1028 × 1.6 × 10-19 × (π)4 ×(0.02)2) =(102/109 × 0.4 × 3.14 × 0.0004) V d =2 × 10-4 m / s

Q. A wire of diameter $0.02 m$ contains $1 0^{28}$ free electrons per cubic metre. An electrical current of 100 flows through the wire. The drift velocity of the free electrons in the wires is nearly

$1 0^{- 19} m / s$

$5 \times 1 0^{- 10} m / s$

$2 \times 1 0^{- 4} m / s$

$8 \times 1 0^{3} m / s$

By using $V_{d} = \frac{I}{n e A}$
$= \frac{100}{1 0 ^{28} \times 1.6 \times 1 0 ^{- 19} \times \frac{π}{4} \times ( 0.02 ) ^{2}}$
$= \frac{1 0 ^{2}}{1 0 ^{9} \times 0.4 \times 3.14 \times 0.0004}$
$V_{d} = 2 \times 1 0^{- 4} m / s$

Q. A wire of diameter 0.02m contains 1028 free electrons per cubic metre. An electrical current of 100 flows through the wire. The drift velocity of the free electrons in the wires is nearly

10−19m/s

5×10−10m/s

2×10−4m/s

8×103m/s