AC Fundamentals, Circuit and Circuit Theory
The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of

Iron loss in core
Capacitive effect between adjacent coil turns
Increase in temperature
Skin effect

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AC Fundamentals, Circuit and Circuit Theory
The series and parallel resonance on L-C circuit' differs in that

Series resonance needs a high-resistance source for sharp increase in current
Series resistance needs a low-resistance source for sharp rise in current
Parallel resonance needs a low-resistance source for a sharp rise in line current
Parallel resonance needs a low-resistance source for a sharp increase in impedance

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