Question

a long straight wire of resistance R , radius 'a' and length 'L' Carrie's a constant current 'I' .The poynting vector for the wire is​

Answer 1

Explanation:

Since,

Electric field in wire,

E=

L

V

=

L

IR

(V=IR, ohm's Law)

and,

H=

2πa

I

(current distributed along surface of wire)

So, magnitude of poynting vector,

S

S=EH=

2πaL

I

2

R