The inductivity of a resistor depends on the resistor design and the material properties. Inductivity describes the effects of the magnetic properties of a resistor or coil. A coil has an inductivity L = 1 Henry when a change in the current di = 1 A/s results in a voltage of U = 1 V in the coil (1 H = 1 [Vs/A]). Wire-wound resistors are often single-layer cylindrical or flat coils. Since they lack an iron core, their inductivity is mostly negligible. Inductivity rises when using ferromagnetic support elements. Cast iron and steel grid elements are of relatively low inductivity due to the wave-type shape of the resistance conductor (the forward and return conductors are arranged in parallel thus setting off their magnetic effect). The inductivity found is caused by the internal inductivity of the conductor, asymmetrical structures, leakage fields and the magnetic properties of the resistor conductor. The prototype of a low-induction resistor is a resistor with bifilar winding where the forward and return conductors are arranged in parallel over their entire length. However, this design is not possible in case of higher voltages because insulation between the conductors and at the connecting points must be designed for the voltage to be applied. This will require diagonal winding with two parallel windings in opposite directions whose magnetic effect is therewith neutralized. If winding is perfect, they will meet after half winding at a point with equipotential and thus do not require electrical insulation.