Calculating Poynting Vector in Long Resistive Rod

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Homework Statement

Consider a long resistive rod, exhibiting resistance R, of length l and radius r. Calculate the magnitude and direction of the Poynting vector (neglecting edge effects) and relate the rate of energy transfer between the rod and its exterior to the total power dissipated in the rod.

Homework Equations

The Attempt at a Solution

Not sure how to even go about starting this?! Any help please?

I know that N = 1/mu o E x B, but here we aren't given an E or B field?! What to do ?

Thanks!

 

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anyone?