Problem solved, never mind! Thank you for your help though, Astronuc!
Is this correct ?
The resistance R = 19.74 ohms for V = 15 V and I = 0.76 A is correct, and the resistivity for copper is correct.
R = [itex]\rho[/itex](L/A), is correct.
It seems the math is also correct. Check to make sure the diameter is correct. 0.44 mm dia. => 0.22 mm rad. = 0.00022 m.
Problem solved. The instructor had to edit something since it used another value for copper.
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