Question

Current density in a copper wire is
2.5 -
108
A/m2
. If 8 A current is flowing
through it diameter of the wire is

Answer 1

Answer:

Number density of free electrons in a copper conductor, n = 8.5 × 1028 m - 3 Length of the copper wire, l = 3.0 m

Area of cross-section of the wire, A = 2.0 × 10 - 6 m2

Current carried by the wire, I = 3.0 A, which is given by the relation,

I = nAeVd

Where,

e = Electric charge = 1.6 × 10 - 19 C

Vd = Drift velocity

Therefore, the time taken by an electron to drift from one end of the wire to the other is 2.7 × 104 s.

Answer 2

Explanation:

J=I/A

A=I/J

Pi*R²= I/J

R2=I/J*pie

= 8/2.5*10^8*3.14

R2 = 1.01*10^-8 m

R = 1*10^-4 m

2R = 2*10^-4 m

Ans is 0.2 mm