19. The resistance of the coil is given by R= ρL/A, where Lis the length of the wire, is the resistivity of copper, and Ais the cross-sectional area of the wire. Since each turn of wire has length 2πr, where ris the radius of the coil, then L= (250)2πr= (250)(2π)(0.12 m) = 188.5 m. If rwis the radius of the wire itself, then its cross-sectional area is
This is the end of the preview.
access the rest of the document.