Question

The drift velocity of electrons in silver wire with cross-sectional area $3.14\times {10}^{-6}{m}^2$ carrying a current of $20A$ is. Given atomic weight of $Ag=108$, density of silver $=10.5\times {10}^{3}kg/m^3$.

• A. $2.798\times {10}^{-4}m/sec.$
• B. $67.98\times {10}^{-4}m/sec.$
• C. $0.67\times {10}^{-4}m/sec.$
• D. $6.798\times {10}^{-4}m/sec.$

Answer 1

Answer: (D)

$6.798\times {10}^{-4}m/sec.$

Number of electron per kg of silver $=\frac{6.023\times {10}^{26}}{108}$
Number of electrons per unit volume of silver.
$n=\frac{6.023\times {10}^{26}}{108}\times 10.5\times {10}^3$
$v_d=\frac{I}{neA}$
$=\frac{20}{6.023\times {10}^{26}\times 10.5\times {10}^3\times 1.6\times {10}^{-19}\times 3.14\times {10}^{-6}}\times 108$
$=6.798\times {10}^{-4}m/sec$.