The ratio of the inductance L to the resistance R of a coil remains constant for different winding arrangements in the same volume and shape. It makes sense to define this value as a figure of merit to distinguish different coil structures. The quality factor Q is defined by this ratio.

对于一个线圈，当圈数和形状相同时，在不同绕线排列的情况下，线圈电感L和电阻R的比值保持恒定不变。把这个值用来区分不同线圈的结构是非常有意义的。这个值就是品质因数Q。

the voltage, which is induced by the same current in an inductor scales with the frequency f and thus the apparent power in the device. The general definition of the quality factor is based on the ratio of apparent power to the power losses in a device. From this definition, the quality factor of a coil results to:

在频率f下电流在电感中产生感应电压，进而可以输出视在功率。品质因数通常的定义是设备中视在功率和功率损耗的比值。由这个定义可以导出线圈的品质因数：

其中ω = 2πf:

The quality factor Q can have a value between 0 and infinity, although it is difficult to obtain values far above 1000 for coils. For mass production you may expect values around 100. A quality factor below 10 is not very useful. These values have to be considered as the typical order of magnitude.

品质因数Q可以在0和无穷大之间取值，但对于一个线圈而言，很难取值到1000以上。对于大批量生产，可以期望该值在100左右。当品质因数低于10时，线圈就基本上发挥不了应有的作用。上述值被作为典型的数量级。

For a fixed operating frequency, the quality factor Q is mainly dependent on the shape and size of the coil as well as the materials used. Quality factors are generally provided for standard coil techniques (e.g. wire-wound coils, PCB coils).

当运行频率固定时，线圈的品质因数Q主要依靠于外形、尺寸和材料。品质因数通常由标准的绕线技术提供（例如：线绕线圈、PCB线圈）