How Do You Calculate Coil Winding Resistance?
A coil of insulated wire with radius R has more than just the usual property of resistance found in any other wire. The commonly known type of electrical resistance is just a matter of multiplying the resistance per length times 2πR times the number of turns in the coil. The more subtle resistance of coils is that a change in current through the coil generates a magnetic field that opposes that very change. This property, called “inductance,” is measured in henries, after the magnetic induction pioneer Joseph Henry. One henry equals one tesla-meter-squared per ampere. Inductance for a coil, or solenoid, is L = μAN^2/l, where μ is the magnetic permeability constant, A is the cross section of the solenoid, l is its length, and N is the number of turns in its coil. Draw a diagram of a circuit with a DC power source, an inductor (a coil), and a resistor. Assume the electrical resistance in the coil is negligible aside from its inductance. Suppose that the cross section of the coil is 20 cm
