Non-ohmic, in the context of electrical circuits and components, refers to elements or devices that do not follow Ohm’s Law, which describes a linear relationship between voltage (V), current (I), and resistance (R) in many materials and components.
In an “ohmic” or “ohmic behavior” scenario:
- The current through the component is directly proportional to the voltage applied across it.
- The resistance remains constant, regardless of the voltage or current.
Non-ohmic behavior, on the other hand, implies that the component’s resistance or current-voltage relationship is not linear and may vary with voltage, current, temperature, or other factors.
Common examples of non-ohmic devices include:
- Diodes: Diodes are semiconductor devices that allow current to flow in one direction and block it in the opposite direction. Their voltage-current characteristics are highly nonlinear.
- Transistors: Transistors are semiconductor devices used for amplification and switching. Their behavior is complex and nonlinear.
- Thermistors: Thermistors are temperature-sensitive resistors that exhibit highly nonlinear resistance changes with temperature.
- Light-Emitting Diodes (LEDs): LEDs are semiconductors that emit light when current flows through them. Their voltage-current relationship is nonlinear.
- Gas Discharge Lamps: Devices like neon lamps have a nonlinear voltage-current relationship, especially when they begin to emit light.
- Varistors: Varistors are voltage-dependent resistors that change resistance dramatically with applied voltage.
- Non-Linear Resistors: Some resistors are intentionally designed to have nonlinear resistance characteristics for specific applications.
Understanding and working with non-ohmic devices is important in electronics and electrical engineering, as it requires considering more complex models and behavior in circuit analysis. Unlike ohmic devices, where the relationship between voltage and current is straightforward, non-ohmic devices may require specialized equations or datasheets to describe their behavior accurately.