Letter: Blame it on Franklin’s ‘positive’ frame of mind

As an engineer and longtime FT reader, allow me to point out an ambiguity, or dare I say a potential mistake, in the “fuel cells” diagram in the excellent article “Europe carmakers wary of hydrogen ‘hype cycle’”(Report, March 11).

You correctly show the electron flow outside the cell between the anode and cathode. However, electrical “current” flows in the exact opposite direction, between cathode and anode.

This contradiction is said to arise from perhaps America’s greatest polymath, Benjamin Franklin. After expertly investigating electricity, Franklin had to make a somewhat arbitrary decision — which he had no way of verifying experimentally — as to whether the particle, which carried electrical charge, was itself positive or negative. Franklin, being of a positive frame of mind, chose positive; hence current flows from “plus” to “minus”.

As it happens, it was not until many years later that JJ Thomson, the British physicist, and others found that this free particle was the electron, with a “minus” charge, and that Franklin’s choice was hence incorrect. Thus, the standard nomenclature is that while electric current flows from positive to negative outside the cell as in the diagram, the electron flow is from negative to positive.

However, Franklin may have had the last word. In quantum physics — which is proven billions of times a second in each and every mobile phone and computer — a key intellectual component is a virtual positive particle called the “hole” or the absence of an electron. It is this that permits today’s transistor-based devices to function.

Hy Chantz
Scarsdale, NY, US