Voltage

[1], [2] Voltage/(Electrical) Potential difference/electric pressure/electric tension is difference in electric potential between 2 points--what pushes free electrons around circuit, measured in volts UI unit.

In a static electric field, it's work needed per charge unit to move a positive test charge from a first to second point.

Named after Italian physicist Alessandro Volta who invented voltaic pile--1st battery with steady current. Without voltage, free electrons move among atoms randomly, which arent useful.

Using voltage makes free electrons all move in same direction, making current.

Water analogy; Voltage can exist without current: Measuring pressure in a valve's shut without water flowing, we known pipe is pressurized-We're actually measuring is pressure difference between pressure inside pipe and outside.

analogy: comparison of 2 seemingly unrelated things

Global and other voltage variations

Energy meter

Voltage root mean square

Volt unit

1 volt is needed to drive 1 coulomb (~6 quintillion, 242 quadrillion electons across an 1Ω resistor in 1 s.)

To power a 1.5 W bulb via 1.5 V battery, need 1 coulomb = 6.2 quintillion electons from battery to lamp each second to be on.

To power a 0.3 W bulb via 1.5V battery, need 0.2 coulomb = 1.8 quintillion electrons to flow across.

Circuit in series

[1]

This battery has 1.5 potential difference between its 2 terminals. Adding a wire forces all electrons to flow all in the same way.

Adding a component makes the electron work for us as enters it.

Adding a 2nd battery in series will boost electrons as they only flow this path as energy is added, adding voltages: 1.5V+1.5V=3V.

More voltage = more pressure = more pushing force = more elctron flow = bulb glows brighter

Circuit in parallel

[2]

If the batteries are in parallel, path splits and both get same voltage value. Voltage here isn't boosted/combined, both using 1.5 V.

Less voltage (less pressure to push) = dimmer light, but lasts longer.

dim: faint/weak

Manufacture labels

Electrical appliances labels show how much volt are products made for

Measuring

Multimeters/Voltmeters measure voltage.

Connect a circuit in parallel across 2 points of what is measured.

This single battery are 1.5V across, and the bulb voltage given by battery to light.

With 2 lamps, we measure their combined 1.5V and 0.75V across them individually.

It's same for battery connected to an open circuit: Voltage is measured and closing it push free electron around circuit.

voltage synonym = potential difference: how much work is potentialy done by a circuit.

Water analogy 2: With 2 lakes of same lvl, no potential can do work as water won't flow. Raising a lake higher, it'll have potential to flow down to another one in a pipe.

Using a turbine there can power light

Global and other voltage variations

Most countries use 220-240 V. All of North, some if South America, and Africa use 110-127 V, as back first distributed electricity had no standard, so each network had their own frequency and voltage for what they deem as best, til companies and dominated and government made laws to buy products easier and trade with other countries.

This still an issue, but everyone is too relied on their devices.

E.g. If an US dryer (rated at 110 V) plugged in Europe (220+ V) burns out as too much voltage/pressure is given.

But some products can be used in diffferent voltages.

E.g. This laptopt charger can be used on 100-240V but left one is rated 220-240V.

Energy meter

We measure voltage from sucket to see it changes a bit as electricity demand varies.

Voltage root mean square

Voltage root mean square or effective voltage (Vrms) is a way to measure how strong is an AC signal's voltage (the effective voltage), mainly in sinusoidal waveforms. It represents the equivalent DC voltage that can make the same amount of power in a resistive load as the AC voltage. For a sinusoidal voltage, the RMS value is calculated by dividing the peak voltage by the square root of 2 (approximately 1.414) or multiplying it by 0.707.

Voltage root mean square formula: Vrms = Vpk/√2

Peak voltage

Peak voltage (Vpk) is the max instant voltage a waveform reaches from the 0 level--what's seen at the highest point on an oscilloscope.

Peak voltage formula: Vpk = √2 x Vrms

Average voltage

Average voltage (Vavg) is an output voltage over a full cycle's average/mean value.

It has formulas for each of the 3 rectifier circuits:

Half-wave rectifier (only positive half passes) formula: Vavg = Vpk/π
Full-wave rectifier (both halves are positive) formula: Vavg = Vpk/π
Bridge rectifier (same as full-wave, but uses 4 diodes) formula: Vavg = 2Vpk/π

[3] The process to find an AC waveform's average voltage is very akin as to find its RMS value, except is that the instantaneous values aren't squared and we don't find the square root of the summed mean.

The average voltage/current of a periodic waveform (whether a sine, square, triangular waveform) is the equivalent to an alternating waveform's DC value--wave's the steady part.

The average/mean value is defined as: “the area's quotient under the wave by respect to time“--the averaging of all instantaneous values along time axis (time = 1full period (T).

Average voltage graphical method:

Peak inverse voltage

Peak inverse voltage (PIV) or peak reverse voltage (PRV) is the max reverse voltage a diode/other semiconductor device can resist without breaking down if reverse biased--it's the negative peak voltage. It's a crucial to ensure a device doesn't get damaged by excessive reverse voltage.

References

[1] Voltage Explained - What is Voltage? Basic electricity potential difference - YT
[2] Wikipedia
- [2.1] Peak inverse voltage
- [2.2]
- [2.3]
- [2.4]
[3] Average voltage - Electronics Tutorial
- [3.1]
[4]

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Voltage

Volt unit

Circuit in series

Circuit in parallel

Manufacture labels

Measuring

Global and other voltage variations

Energy meter

Voltage root mean square

Peak voltage

Average voltage

Peak inverse voltage

References

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