[PPRAANet] Why is I the symbol for electric current?

[Dennis Major]

The conventional symbol for current is I, which may seem puzzling. It 
originates from the French phrase intensité de courant, or in English 
current intensity. This phrase is frequently used when discussing the 
value of an electric current, especially in older texts; modern practice 
often shortens this to simply current but current intensity is still 
used in many recent textbooks. The I symbol was used by André-Marie 
Ampère himself, after whom the unit of electric current is named, in 
formulating the eponymous Ampère's force law which he discovered in 
1820. The notation travelled from France to England where it became 
standard, although at least one journal did not change from using C to I 
until 1896.

Just in case you ever wondered.

I've been asked the question a few times.

-- 

73

Dennis Major, N0ABC
Laurel ARC VEC, Region #10 Coordinator
PPRAA VE Team Leader