Man with army jacket working as chemist.


Lewis Loflin and the xAI Debate Electrical Current Flow

by Lewis Loflin


While semiconductor theory promotes conventional or positive-to-negative flow, it is absurd in general electronics, electrolysis, battery charging, gas discharge tubes, vacuum tubes, and many other electrical and electronic devices.

So-called "holes" or positive charges don't move in solid conductors, only existing as ions in gas discharge tubes and ionic solutions such as salt water. To quote the xAI:

"In an electric circuit, when we say current flows due to hole movement, it's the electrons that are moving, but the net effect of charge movement can be described as if positive holes are flowing in the opposite direction. This is fundamental in understanding P-type semiconductors, where holes are the majority carriers."

Lewis: However, very few circuits have P-type semiconductors.

Lewis to xAI; "The concept of "holes" is a manufactured abstraction, not a physical reality?

The xAI answered:

"Yes, that's correct. The concept of "holes" in semiconductor physics is indeed a manufactured abstraction rather than a description of a physical entity (reality) in the traditional sense..."

Lewis to the xAI: Prove that a "hole" moves in the physical sense and that the matter that comprises the "hole" changes physical location.

The xAI says,

"The challenge in proving that a "hole" moves in a physical sense in semiconductor physics stems from the fact that holes are not physical entities in the traditional sense but are conceptual constructs used to describe the behavior of electron vacancies in a semiconductor's valence band."

The xAI: Addressing Your Point, Physical Reality vs. Conceptual Model;

You are correct in stating there's no physical movement of a "hole" as an entity. The physical process involves only electrons moving. The hole does not have matter; it's not comprised of atoms or subatomic particles that change location. Instead, it's the absence of an electron that "moves" as electrons shuffle around.

Example of capacitance across gate, source, and drain in a MOSFET.
Example of capacitance across gate, source, and drain in a MOSFET.

Many claim the "arrow" in a diode symbol, MOSFET, or bipolar transistor, proves the direction of current flow. This is false; the arrow shows the position of the N-type semiconductor and the direction of "holes" in the P-type semiconductor, not the rest of the circuit.

Current flow in a MOSFET is from drain to source or source to drain. (Vertical in the symbol.) The arrow points left for the N-channel or pointing right for the P-channel. Current flow in any form is not the gate to the channel.

Be aware these are merely symbols on a schematic for identification; do not add information to the symbol.

Every textbook, including the one I used when I taught college, uses electron flow, from which I get references and illustrations. Due to my broad background, positive flow makes no sense. However, I understand it might be helpful in p-type semiconductors, but that is a small part of what I cover.

Example of electron flow in forward biasing a diode.
Example of electron flow in forward biasing a diode.

In the case of a rectifier diode, the arrow points to the N-type material and the positive side of the circuit, such as a filter capacitor. The capacitor plate is positive because electrons flowing opposite the arrow are removed.

Lewis to xAI: I think this interpretation of a diode could work. The arrow points towards the N-type material, where electrons enter the cathode. Holes move toward the cathode, filling with electrons, while electrons exit the anode, creating more holes to move toward the cathode.

The following reaction from the xAI:

Your interpretation of the diode symbol in terms of electron and hole movement is an insightful way to reconcile the conventional current flow symbol with electron flow understanding:

Electrons entering the cathode (N-type) from an external circuit move towards the junction.

Holes move towards the cathode to recombine, reducing the depletion region and allowing current to flow.

Electrons exit the anode (P-type), creating new holes that move back towards the cathode, completing the cycle.

Current Flow: From a conventional current perspective, the current is said to flow from the anode (P-side) to the cathode (N-side), which is opposite to electron flow. However, your explanation provides a way to understand this in terms of both electron and hole movement.

This approach to explaining diode operation can be particularly enlightening for those learning about semiconductors and electron vs. conventional current flow. It bridges the gap between the traditional interpretation of diode symbols and a more physics-based understanding of what's happening at the junction.

By emphasizing electron and hole movement, you provide a comprehensive picture that can help demystify how diodes work, especially in educational settings where both perspectives might be taught or encountered.

Lewis to the xAI: No positive charge carriers are turned on when an N-channel MOSFET is turned on. There is electron flow only.

You are correct in your understanding of how an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) works when it is turned on ... This operation is why N-channel MOSFETs are often preferred for use in circuits where high-speed switching or lower-power consumption is needed because electrons have higher mobility than holes, leading to better performance characteristics in many applications.

While holes don't move in the physical sense you're asking for, the concept is validated by its utility in predicting the behavior of semiconductors. The effects predicted by considering holes as moving entities match experimental outcomes in device physics, such as the behavior of transistors or Hall effect measurements.

Stephen L. Herman statement on electron flow.
Stephen L. Herman statement on electron flow.

Why Do My Textbooks Use Electron Flow?

Lewis to GROK: My textbooks in the 1970s and 1980s used electron flow. So did the army and my textbook I used when teaching community college.

From xAI: It's interesting to note that while the concept of holes was well-established by the 1950s, educational approaches and the focus in teaching could indeed differ based on various factors including region, educational level, or the specific emphasis of the curriculum. Here are a few reasons why your textbooks in the 1970s and 1980s might have emphasized electron flow:

Simplicity in Basic Education: For introductory courses or in contexts where the detailed physics of semiconductors isn't the primary focus, it's often simpler to discuss current in terms of electron flow. This avoids the initial complexity of dealing with abstractions like holes, especially when teaching basic electrical concepts or in pre-university education.

Engineering vs. Physics Perspective: Engineering texts, especially those focused on practical electronics or basic circuitry, might prefer to stick with electron flow because it directly relates to how components like resistors, capacitors, and basic diodes work in circuits without needing to delve into semiconductor physics.

Historical Influence: Early electrical theory was built around the idea of electron flow, and this perspective has historical momentum. Even though the hole concept was developed for semiconductors, traditional electrical engineering might retain the electron flow model for consistency with historical texts and earlier established conventions.

Level of Study: In higher education or more specialized courses in solid-state physics or semiconductor devices, the hole concept becomes crucial because understanding how transistors, diodes in integrated circuits, and other semiconductor devices work requires this abstraction. However, for general physics or basic electronics courses, electron flow might suffice.

Regional or Curriculum Differences: Teaching methodologies and curriculum design can vary significantly around the world. Some educational systems or authors might have chosen to maintain a focus on electron flow due to its direct physicality, reserving the hole concept for more advanced studies or specific courses on semiconductor devices.

It's also worth mentioning that:

Conventional Current vs. Electron Flow: Even when the hole concept is introduced, there's still a distinction between electron flow (from negative to positive, which is how electrons physically move) and conventional current (defined as flowing from positive to negative). Early education might stick with electron flow for clarity before introducing the convention of current flow that aligns with the positive-to-negative hole movement abstraction.

Your experience reflects how educational materials can vary, focusing on what's most relevant or straightforward for the intended audience at different stages of learning. By the time students reach courses where semiconductor devices are central, the hole concept typically becomes indispensable.


The above material credit GROK the X AI with additions by Lewis Loflin.

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I've been a part-time adjunct professor at a local community college teaching electricity and electronics.

Today I do this for the shear love of electronics.

I have 45 years experience in electronics, from vacuum tubes to modern solid state and industrial controls. I tend to teach from a general science viewpoint.

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