Editing Resistor (section)

== Nonideal properties ==
Practical resistors have a series [[inductance]] and a small parallel [[capacitance]]; these specifications can be important in high-frequency applications. And while even an ideal resistor inherently has [[Johnson noise]], some resistors have worse [[Noise (electronics)|noise]] characteristics and so may be an issue for [[low-noise amplifier]]s or other [[Sensitivity (electronics)|sensitive]] electronics.

In some precision applications, the [[temperature coefficient]] of the resistance may also be of concern.

The unwanted inductance, excess noise, and temperature coefficient are mainly dependent on the technology used in manufacturing the resistor. They are not normally specified individually for a particular family of resistors manufactured using a particular technology.<ref>A family of resistors may also be characterized according to its ''critical resistance.'' Applying a constant voltage across resistors in that family below the critical resistance will exceed the maximum power rating first; resistances larger than the critical resistance fail first from exceeding the maximum voltage rating. See {{cite book |author=Middleton, Wendy |author2=Van Valkenburg, Mac E. |title=Reference data for engineers: radio, electronics, computer, and communications |edition=9 |publisher=Newnes |year=2002 |isbn=0-7506-7291-9 |pages=5–10}}</ref> A family of discrete resistors may also be characterized according to its form factor, that is, the size of the device and the position of its leads (or terminals). This is relevant in the practical manufacturing of circuits that may use them.

Practical resistors are also specified as having a maximum [[Power (physics)|power]] rating which must exceed the anticipated power dissipation of that resistor in a particular circuit: this is mainly of concern in power electronics applications.
Resistors with higher power ratings are physically larger and may require [[heat sink]]s. In a high-voltage circuit, attention must sometimes be paid to the rated maximum working voltage of the resistor. While there is no minimum working voltage for a given resistor, failure to account for a resistor's maximum rating may cause the resistor to incinerate when current is run through it.