The core material, the core diameter, the length of the coil and the number of turns of wire used to wind the coil 

The core material, the number of turns used to wind the core and the frequency of the current through the coil

The core diameter, the number of turns of wire used to wind the coil and the type of metal used for the wire

The core material, the core diameter, the length of the coil and whether the coil is mounted horizontally or vertically



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