Non-Ohmic Behavior

Definition

Non-ohmic behavior refers to the characteristic of materials or devices that do not obey Ohm's Law, meaning their current-voltage relationship is not linear. This behavior is significant because it indicates that resistance varies with voltage or current, leading to unique and often complex electrical characteristics that are important in various applications and device designs.

5 Must Know Facts For Your Next Test

1. Non-ohmic devices like diodes and transistors exhibit a nonlinear relationship between voltage and current, unlike resistors which follow Ohm's Law.
2. The resistance of non-ohmic materials can change with temperature, voltage, or current, making their analysis more complex than that of ohmic materials.
3. In non-ohmic behavior, the I-V curve does not produce a straight line; instead, it may curve or exhibit distinct regions such as thresholds or saturation.
4. Examples of non-ohmic components include thermistors, varistors, and light-dependent resistors (LDRs), each having unique I-V characteristics based on their operational principles.
5. Understanding non-ohmic behavior is crucial for designing circuits that use nonlinear elements, as it affects how those circuits function under varying loads and conditions.

Review Questions

• How does non-ohmic behavior differ from ohmic behavior in electrical components?
  • Non-ohmic behavior differs from ohmic behavior primarily in the relationship between voltage and current. While ohmic components, like resistors, maintain a constant resistance regardless of voltage or current levels, non-ohmic components exhibit changing resistance depending on these factors. This means that in non-ohmic devices, the current-voltage graph does not yield a straight line but instead displays a curve reflecting the material's nonlinear characteristics.
• Discuss the implications of non-ohmic behavior for circuit design involving semiconductor devices.
  • The implications of non-ohmic behavior in circuit design are significant, especially when incorporating semiconductor devices such as diodes and transistors. Designers must account for the nonlinear I-V characteristics when predicting circuit performance. This means careful consideration of how changes in input voltage will affect current flow, leading to potential challenges in ensuring consistent operation under different conditions. Non-linear elements can introduce complexities such as distortion or threshold effects that require specific design strategies to mitigate.
• Evaluate the role of temperature in affecting the non-ohmic behavior of certain materials and its impact on their applications.
  • Temperature plays a crucial role in affecting the non-ohmic behavior of materials like thermistors. As temperature changes, the resistance of these materials can significantly increase or decrease, altering their current-voltage characteristics. This variability can impact their applications in temperature sensing or circuit protection. In design scenarios, understanding how temperature influences these properties is essential for ensuring reliable operation and accurate readings in electronic devices that rely on non-ohmic components.

Related terms

Ohm's Law:

A fundamental principle stating that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, represented as $$V = IR$$.

Resistor:

A passive electrical component that provides resistance within a circuit, typically exhibiting ohmic behavior under constant conditions.

Diode: A semiconductor device that allows current to flow in one direction only and demonstrates non-ohmic behavior by having a nonlinear current-voltage characteristic.