2- A copper wire of 3mm diameter with conductivity of 6.7 10' (0.M), and electron mobility of 0.0064 m2 /V sec. Is subjected to an electric field of 30 mV/m. Find (a) the charge density of free electrons, (b) the current density, (c) current flowing in the wire, (d) the electron draft velocity.

Respuesta :

Answer:

a)  [tex]n=5.98*10^{26}/m^3[/tex]

b)  [tex]i=2010000A/m^2[/tex]

c)  [tex]I_w=14.207A[/tex]

d)  [tex]V_e=1.92*10^{-4}m/s[/tex]

Explanation:

From the question we are told that:

Diameter [tex]d=3mm=>3*10^{-3}[/tex]

Conductivity [tex]\sigma= 6.7 10^7 (0.M),[/tex]

Electron mobility [tex]\phi= 0.0064 m2 /V sec[/tex]

Electric field [tex]E= 30 mV/m[/tex]

a)

Generally the equation for Charge Density is mathematically given by

[tex]\phi=\frac{\sigma}{n e}[/tex]

Therefore

[tex]n=\frac{\sigma}{\phi e}[/tex]

[tex]n=\frac{6.7 10^7}{1.6*10^{-19} *0.0064}[/tex]

[tex]n=5.98*10^{26}/m^3[/tex]

b)

Generally the equation for current density is mathematically given by

[tex]i=\sigma*E[/tex]

[tex]i= 30*10^{-3] *6.7 10^7[/tex]

[tex]i=2010000A/m^2[/tex]

c)

Generally the equation for current in wire is mathematically given by

[tex]I_w=iA[/tex]

[tex]I_w=i*\pi r^2[/tex]

[tex]I_w=(2010000)*\pi( 1.5*10^{-3})^2[/tex]

[tex]I_w=14.207A[/tex]

d)

Generally the equation for electron draft velocity. is mathematically given by

[tex]V_e=\phi E[/tex]

[tex]V_e=(0.0064)*(30*10^{-3})[/tex]

[tex]V_e=1.92*10^{-4}m/s[/tex]