VCC英文全称是什么？为什么电压是Voltage，但符号却用U？为什么电流是Current，符号却用I？

In Electronics, What Does “VCC” Stand For?

VCC stands for “voltage at the common collector.” 

The letter “V” on a circuit stands for the supply voltage. The letters “CC” indicate that the supply voltage is positive or negative. If the charge is positive, its circuit is a Negative-Positive-Negative circuit, and if negative, it is a Positive-Negative-Positive circuit.

VCC is more commonly labelled V+, VS+ or VDD (voltage drain drain). The common collector is responsible for the power coming from the base and the collector, while output is from the emitter-collector circuit. Integrated circuits with bipolar transistors have positive and negative power supplies. The positive supply is called “VCC” while “VEE” is the negative power supply.

Reference: VCC

Voltage is the Cause, Current is the Effect

Voltage attempts to make a current flow, and current will flow if the circuit is complete. Voltage is sometimes described as the ‘push’ or ‘force’ of the electricity, it isn’t really a force but this may help you to imagine what is happening. It is possible to have voltage without current, but current cannot flow without voltage.

Reference: https://www.electronicsclub.info/voltage.htm

Where does U for voltage come from?

Q:

I believe in Europe the letter U is commonly used for voltage in (eg.) Ohm’s law \$U = I × R \$. I think I understand where the letter V came from, commonly used in North America. But what’s the story with U?

A1:

The best reason I’ve heard is to avoid this: –

V = 2 V (which of course is meant to say “voltage = 2 volts”)

U = 2 V sounds more sensible after all we use a different symbol for current (I) and also amps. Voltage is a bit on its own – we wouldn’t say “amps = 2 amps” or “current = 2 currents”.

It seems to me this is the sensible reason for choosing U over V but having said that I never use “U”! Maybe I should?

A2:

_{Radoslaw J.
PhD., Eng.; R&D Magnetic and Power Electronic Engineer, Project Leader at ABB PL Corporate Research Center}

Both of voltage description “U” and “V” are proper, however it must be mentioned that in European notation “U” describes voltage source while “V” describes rather voltage potential. It means that U = V1 – V1 (voltage is a difference between voltage potentials). I agree that in IEEE and American standards voltage is described by “V” letter.
Very similar situation is with other electric symbols also (e.g. resistors, capacitors, current sources, etc.), where European and American standards are different.

Why is current represented by the letter I in electronics?

One explanation I was given was that when a letter was needed to represent current in formulas, C had already been used, and it was decided to use the next unused letter of the alphabet, which was I. However, I prefer the other explanation, which is that in the early days of investigations into electricity, what we now call current was called Intensity, hence the letter I. It should never be confused with Impedence, the symbol for which is Z.

References:

[1] https://electronicsclub.info/

[2] https://www.allaboutcircuits.com/

[3] https://electronics.stackexchange.com/