Discussion Overview
The discussion revolves around the characteristics of non-Ohmic materials, particularly focusing on the "vanishingly small" extra terms in the context of Ohm's law, and the nature of slight non-linearities in Ohmic materials. Participants explore examples of non-Ohmic behavior and seek information on the magnitude of non-linear terms in Ohmic conductors.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant notes the existence of "vanishingly small" extra terms in the context of Ohm's law for non-Ohmic materials like superconductors.
- Another participant mentions that traditional non-Ohmic materials include semiconductors, highlighting the exponential nature of the V-I curve in p-n junction diodes.
- A participant suggests that high current density in Ohmic materials could lead to transient heating effects, which might introduce non-linearity, while still maintaining Ohmic behavior by using temperature-dependent resistivity.
- Examples of Voltage Dependent Resistors (VDRs) and Negative Temperature Coefficient Resistors (NTCs) are provided, illustrating how these components exhibit non-linear behavior under certain conditions.
- The Positive Temperature Coefficient Resistor (PTC) is also mentioned, with its behavior of increasing resistance with temperature being discussed in the context of controlling startup currents.
Areas of Agreement / Disagreement
Participants present multiple viewpoints regarding the nature of non-linearities in Ohmic materials and the characteristics of non-Ohmic materials. There is no consensus on the specific magnitude of the "vanishingly small" terms or the conditions under which non-linearities occur.
Contextual Notes
Some claims depend on specific definitions of Ohmic and non-Ohmic behavior, and the discussion does not resolve the extent to which transient effects impact the linearity of Ohmic materials.