flowing in only part of the loop. The flux will increase over a period of a few seconds, asthe electrons get around the loop. Figure 10-2 is an approximate graph of the overallmagnetic field versus time. After about 5.5 seconds, current is flowing around the wholeloop, and the magnetic field has reached its maximum.184 Inductance10-1A huge loop of wireillustrates the principle ofinductance. See text.A certain amount of energy is stored in this magnetic field. The ability of the loop tostore energy in this way is the property of inductance. It is abbreviated by the letter L.Practical inductorsOf course, it’s not easy to make wire loops even approaching a million miles in circum-ference. But lengths of wire can be coiled up. When this is done, the magnetic flux 10-2Relative magneticflux in the hugewire loop, as afunction of time inseconds.