a wire of 5 8 metre long,2 millimetre diameter carries 750 milliampere current when 22 mV potential difference is applied - Physics - Current Electricity

Question

a wire of 5 8 metre long,2 millimetre diameter carries 750
milliampere current when 22 mV potential difference is applied at
its ends if drift speed of electrons is found 1 7 into 10^-5 metre
per second then find
current density and number of free electrons per unit volume
answer-
current density=2 4*1)^5A/m square
n=8 8*10^28

Vaibhav Tiwari · Accepted Answer

Dear Student,

length, l=5
8 mdiameter, d=2 mm=2×10-3 mradius, r=1×10-3 mcurrent, I=750 mA=750×10-3 Apotential difference, V=22 mV=22×10-3 Vdrift speed, vd=1
7×10-5 m/scurrent density, J=IAarea, A=πr2A=3
14×1×10-32=3 14×10-6 m2J=750×10-33
14×10-6=2 38×105 A/m2vd=Jnen=Jvden=2 38×1051
7×10-5×1 6×10-19=8 7×1028