Hobby Why I?

[Moley]

In a few minutes of boredom in a switchroom today we discussed why 'I' is used for current. If you think of Ohms law V & R are pretty obvious but why 'I' for current? If we were discussing inductance I could understand it but that's measured in henrys. So, without cheating and Googling it anyone know the significance of the 'I'? No doubt it's obvious but we couldn't think of it.
Also why couldn't I post this without a prefix????? Had to pick hobby

 

[James]

The conventional symbol for current is I, which originates from the French phrase intensité du courant (current intensity). Current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820).

from the internet, not me!!

 

[littlespark]

From the same source, as in, I googled it… we use the Latin alphabet letter Omega instead of an O for Ohms, as it would cause confusion between “O” and “0” (zero)

So why have we got an I anywhere which can be confused for a 1?

 

[Moley]

So you both cheated. I was hoping someone would actually know rather than look it up. Well, at least I can go in to work tomorrow and tell everyone why it's an 'I' and tell them I didn't look it up

 

[James]

I racked my brain trying to remember or figure it out for myself and failed.
Then I resorted to cheating.
Although to be fair, I did name my source instead of pretending to have supreme knowledge!

 

[EalingBadger]

Also, and as a slight digression from the OP's original question, spare a thought for the poor old electrical / electronics engineer who has to cope with the use of both 'i' and 'j' in various different context dependant ways.

Specifically, mathematicians traditionally use 'i' to represent the square root of minus one when manipulating imaginary / complex numbers:

Imaginary unit - Wikipedia - https://en.wikipedia.org/wiki/Imaginary_unit

Unfortunately for those of an electrical bent they found that, upon needing to start employing complex numbers in their own work, the mathematicians had already beaten them to it with 'i' (and anyway the electrical guys had already opted for 'I' to designate current) so, in order to avoid potentially dangerous confusion on both these counts, the letter 'j' was adopted for use in the electrical professions.

My source?

My 'A' level maths & physics teachers in 1975, so I didn't cheat and hereby (and in all innocence ) nominate myself for the Supreme Knowledge award.

Further reading for those that care:

Elementary vectors for electrical engineers : Stubbings, G. W. (George Wilfred), 1887-1951 : Free Download, Borrow, and Streaming : Internet Archive - https://archive.org/details/elementaryvector00stub/page/68/mode/2up

 

[Marvo]

I was going to guess the 'C' was already used to denote a Constant in formulas therefor it couldn't be used for Current. I had no idea why I was chosen though.

 

[w0z]

The C word has long since been hijacked...
(or so j imagine)

 

[sunray]

Well...

How many times have we heard something like 'turn the current on' in a film? especially horror films. Historically 'current' has been used to describe electricity, hence Current Velocity (Voltage) and Intensity (current). However if that explanation had any truth I'd have thought voltage would have been intensity and current would be velocity (compare with water pressure I and flow V)
I even used to see temporary warning signs on building sites 'Warning current on'.

So the the other explanation I believed at some dim distant past? Current Induced into a load.

I see Intensity takes the crown in an early reply

 

[w0z]

Ampere used the "i" notation in his original work and it stuck. I hadn't heard the intensity explanation before reading this thread.
The Intensity is referred to here on page 43
( I was curious as to from where the explanation originated - sorry!)

 

[Mike Johnson]

Well at least the topic is current.



I will get my coat.

 

[7029 dave]

Because my lecturer at southgate tech college told me. circa 1980