The electrical resistance of the coil wire. It determines how much heat the coil produces during operation and how much voltage the device needs to reach peak current. Lower resistance means less wasted heat and more efficient energy delivery to the magnetic field. Measured in Ohms (Ω). Resistance decreases with thicker wire (lower AWG number) and increases with temperature.
Coil current does not switch on instantly; it builds up along this curve, set by the coil's L/R time constant. It reaches about 63% of full after one time constant, 95% after three, and 99% after five. If the pulse is at least about three time constants long, the current has essentially finished building, so the pulse is complete.
