Question

A copper wire has a cross-sectional area of 0.80 × 10-6 m2. The number density of electrons for copper is 9.5 × 10^28 m-3. A current of 18 A flows through the wire. Calculate the mean drift velocity of the free electrons in the wire. *

Answer 1

Answer: 1.480 mm/s

Step-by-step explanation:

Given

Cross-sectional area
`A=0.80* 10^(-6)\ m^2`

Number density(no of charges per unit volume)
`n=9.5* 10^(28)\ m^(-3)`

Current
`I=18\ A`

We know, drift velocity is given by

`\Rightarrow v_d=(I)/(neA)\\\Rightarrow v_d=(18)/(9.5* 10^(28)* 1.6* 10^(-19)* 0.8* 10^(-6))\\\Rightarrow v_d=(18* 10^(-3))/(12.16)=1.480\ mm/s`