A copper wire of length 1 m and uniform cross sectional area 5 × 10-7 m 2 carries a current of 1 A. Assuming that there are 8 × 1028 free electrons per m 3 in copper, how long will an electron take to drift from one end of the wire to the other?

Question

A copper wire of length 1 m and uniform cross sectional area 5 × 10-7 m 2 carries a current of 1 A. Assuming that there are 8 × 1028 free electrons per m 3 in copper, how long will an electron take to drift from one end of the wire to the other? (A) 0.8 × 103 S (B) 1.6 × 103 S (C) 3.2 × 103 S (D) 6.4 × 103 S

Tardigrade Admin · Accepted Answer

t =(l/ v d ) I =neAvd v d =( I / neA ) t =(l neA / I ) t =(1 × 8 × 1028 × 1.6 × 10-19 × 5 × 10-7/1) t =6.4 × 103 s

Q. A copper wire of length $1 m$ and uniform cross sectional area $5 \times 1 0^{- 7} m^{2}$ carries a current of $1 A$ . Assuming that there are $8 \times 1 0^{28}$ free electrons per $m^{3}$ in copper, how long will an electron take to drift from one end of the wire to the other?

$0.8 \times 1 0^{3} S$

$1.6 \times 1 0^{3} S$

$3.2 \times 1 0^{3} S$

$6.4 \times 1 0^{3} S$

$t = \frac{l}{v _{d}}$
$I = n e A v_{d}$
$v_{d} = \frac{I}{n e A}$
$t = \frac{l n e A}{I}$
$t = \frac{1 \times 8 \times 1 0 ^{28} \times 1.6 \times 1 0 ^{- 19} \times 5 \times 1 0 ^{- 7}}{1}$
$t = 6.4 \times 1 0^{3} s$

Q. A copper wire of length 1m and uniform cross sectional area 5×10−7m2 carries a current of 1A. Assuming that there are 8×1028 free electrons per m3 in copper, how long will an electron take to drift from one end of the wire to the other?

0.8×103S

1.6×103S

3.2×103S

6.4×103S