Why is V the symbol for voltage?

[spareine]

I was wondering why V is a common symbol for voltage. The symbol is not named after the unit volt, because it is older than the volt unit, which dates from 1874. Before that, voltage was potential. In 1828 Green used the symbol V for the potential function which he introduced in his essay on electricity. In 1785 Laplace used the symbol V for M/r, in his Théorie des attractions. Laplace used V without giving it a name, but to us it is the gravitational potential except for a constant. In 1788, Lagrange expressed conservation of vis viva (living force, energy) as T+V = const, with T=1/2 m v². (Méc. analytique)

So now I am wondering if the symbol V is named after vis viva.

 

[OmCheeto]

I was wondering why V is a common symbol for voltage. The symbol is not named after the unit volt, because it is older than the volt unit, which dates from 1874. Before that, voltage was potential. In 1828 Green used the symbol V for the potential function which he introduced in his essay on electricity.

TLDR

In 1785 Laplace used the symbol V for M/r, in his Théorie des attractions.

Nickt spreken me Frenchy.

Laplace used V without giving it a name, but to us it is the gravitational potential except for a constant. In 1788, Lagrange expressed conservation of vis viva (living force, energy) as T+V = const, with T=1/2 m v². (Méc. analytique)

Nickt spreken me Frenchy again.

So now I am wondering if the symbol V is named after vis viva.

The volt (symbol: V) is the SI derived unit for electric potential (voltage), electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.

You are welcome.

 

[Whovian]

I think the OP stated that the symbol V predated the unit "volt." I can't confirm this since I'm quite rusty on my physics history.

 

[OmCheeto]

I think the OP stated that the symbol V predated the unit "volt." I can't confirm this since I'm quite rusty on my physics history.

I cannot confirm that V predated the volt.

...In 1828 Green used the symbol V for the potential function which he introduced in his essay on electricity.

Although originally published in 1828, there is no guarantee that subsequent transcriptions didn't replace his symbol for volts, with "v".
Therefore, I would have to view the original work.
Green: 14 July 1793 – 31 May 1841

In 1785 Laplace used the symbol V for M/r, in his Théorie des attractions.

This is dated: MDCCCXCIV
which translates to 1894.
The "volt" was given its name in 1881. (Encyclopædia Britannica, Volume 12, page 426)
For the same reason as above, "v" may have replaced what Pierre Simon Laplace originally used.
Laplace: 23 March 1749 – 5 March 1827(wiki)

Laplace used V without giving it a name, but to us it is the gravitational potential except for a constant. In 1788, Lagrange expressed conservation of vis viva (living force, energy) as T+V = const, with T=1/2 m v². (Méc. analytique)

T=1/2 mv² is the equation for kinetic energy. "v" stands for velocity. So this is a bit of a red herring.
Mec. Analytique dated: 1811
Joseph Louis Lagrange: 25 January 1736 – 10 April 1813
And I still don't speak French.

So now I am wondering if the symbol V is named after vis viva.

I'm going to go out on a limb again and say that "V" is named after Alessandro Giuseppe Antonio Anastasio Volta (18 February 1745 – 5 March 1827)

It would make sense to me that after the Volt was given its name, everything published afterwards would use that name, regardless of what was originally used. Imagine the confusion of students if the original symbols were used. Electricity is confusing enough, without having to memorize what every person through history referred to it as.

If Laplace did use "V" for voltage (vis viva), it may have been a happy coincidence.

ps. To the OP, thank you for this question. I should know this stuff. And if you can find the original transcripts of Lagrange and Green, I would very much like to see them. My oldest textbook is only 78 years old.: Introduction to Quantum Mechanics, by Linus Pauling, Cal Tech, and E. Bright Wilson, Harvard. 1935. Fortunately, my math skills are all but gone, so I can't get past page 1.

 

[eachus]

Hmm... In (now old) Electrical Engineering texts I've seen E(electropotential) = IR, W (or P for power) = I^2R, etc. Anyway, the question for me has always been, where did the I for current come from? C is not a good choice, if you are doing integration, but why not A for Ampere?

 

[cabraham]

Hmm... In (now old) Electrical Engineering texts I've seen E(electropotential) = IR, W (or P for power) = I^2R, etc. Anyway, the question for me has always been, where did the I for current come from? C is not a good choice, if you are doing integration, but why not A for Ampere?

The German word for "intensity" is what gave birth to "I" for current. I'm not sure if the quantity was called "current" in the 1830's. I believe it was either Ohm or Kirchoff that used the term "intensity". I haven't read up on this issue for a long time, but I do remember that "I" denotes "intensity".

Claude

 

[OmCheeto]

Hmm... In (now old) Electrical Engineering texts I've seen E(electropotential) = IR, W (or P for power) = I^2R, etc. Anyway, the question for me has always been, where did the I for current come from? C is not a good choice, if you are doing integration, but why not A for Ampere?

I don't know.

hmmm...

google google google

Ah ha! It's those darned French people again...

The conventional symbol for current is I, which 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, after whom the unit of electric current is named, in formulating the eponymous Ampère's force law which he discovered in 1820. The notation traveled from France to Britain, where it became standard, although at least one journal did not change from using C to I until 1896.

André-Marie Ampère
Born 20 January 1775 Parish of St. Nizier, Lyon, France
Died 10 June 1836 (aged 61) Marseille, France

 

[ModusPwnd]

The German word for "intensity" is what gave birth to "I" for current. I'm not sure if the quantity was called "current" in the 1830's. I believe it was either Ohm or Kirchoff that used the term "intensity". I haven't read up on this issue for a long time, but I do remember that "I" denotes "intensity".

Claude

Thx for that. Before you posted this I did a google translate for "current to german" but it started with "s".

 

[the_emi_guy]

Thx for that. Before you posted this I did a google translate for "current to german" but it started with "s".

Its not German, its from French (as OmCheeto pointed out). Ampere was a French physicist.

 

[spareine]

I cannot confirm that V predated the volt.

In 1881 the cgs-system was adopted: "The British Association got the happy idea to designate the various units by the names of scholars to whom we owe the major discoveries that have led to modern electricity, you have followed this path, and now the names of Coulomb, Volta, Ampere, Ohm and Faraday remain closely linked to the daily applications of the doctrine which they were the happy creators " http://seaus.free.fr/spip.php?article964

Although originally published in 1828, there is no guarantee that subsequent transcriptions didn't replace his symbol for volts, with "v". Therefore, I would have to view the original work. This is dated: MDCCCXCIV which translates to 1894. The "volt" was given its name in 1881. (Encyclopædia Britannica, Volume 12, page 426)
For the same reason as above, "v" may have replaced what Pierre Simon Laplace originally used. Laplace: 23 March 1749 – 5 March 1827(wiki)

The work of Green and that of Laplace is mathematical, they do not contain units.

T=1/2 mv² is the equation for kinetic energy. "v" stands for velocity. So this is a bit of a red herring.

Mathematically, gravitational force near a point mass and electrostatic force near a point charge are similar, they obey an inverse square law. Their potentials are similar as well. V=-GM/r and V=(1/4πε)Q/r . Laplace studied gravity, Green studied electricity. The purpose of the links was to illustrate that the symbol V was used for any potential in the 18th and 19th century, and for potential energy (V = const - 1/2 m v²)

I'm going to go out on a limb again and say that "V" is named after Alessandro Giuseppe Antonio Anastasio Volta (18 February 1745 – 5 March 1827)
It would make sense to me that after the Volt was given its name, everything published afterwards would use that name, regardless of what was originally used. Imagine the confusion of students if the original symbols were used. Electricity is confusing enough, without having to memorize what every person through history referred to it as.

Standardization of the units happened late in the 19th century.

 

[spareine]

Anyway, the question for me has always been, where did the I for current come from? C is not a good choice, if you are doing integration, but why not A for Ampere?

Actually, Maxwell chose the symbol C for current in his Treatise on Electricity and Magnetism (p.236), and he assigned the I to the Magnetization (M, today). He had assigned the A already to the vector potential.

 

[DiracPool]

Ah ha! It's those darned French people again...

Qu'est-que c'est?!