**Voltage (V) electrical unit**

**What is a Voltage?**

Electrical Voltage is defined as the electric potential difference between 2-points of an electric field.

Using the water pipe analogy, we can visualize the voltage as a height difference that makes the water flow down.

**Calculation to Electric Field formula:**

*V* = φ_{2} – φ_{1}

**V** = is the voltage between point 2 and 1 in volts (V).

**φ2** = is the electric potential at point-2 in volts (V).

**φ1** = is the electric potential at point-1 in volts (V).

**Volt definition**

Volt is the electrical unit of voltage or potential difference (symbol: V).

1 Volt is defined as energy consumption of 1 joule per electric charge of 1 coulomb.

1V = 1J/C

1 volt is equal to a current of 1 amp times the resistance of 1 ohm:

1V = 1A × 1Ω

**Alessandro Volta**

A Volt unit is named after Alessandro Volta, an Italian physicist who invented an electric battery.

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**Electric Voltage Calculation**

In an electrical circuit, the electrical voltage (V) in volts (V) is equal to the energy consumption (E) in Joules (J).

divided by the electric charge Q in coulombs (C).

**V** = is the voltage measured in volts (V)

**E** = is the energy measured in joules (J)

**Q** = is the electric charge measured in coulombs (C).

**Volt subunits and conversion table**

name | symbol | conversion | example |
---|---|---|---|

microvolt | μV | 1μV = 10^{-6}V |
V = 30μV |

millivolt | mV | 1mV = 10^{-3}V |
V = 5mV |

volt | V | - |
V = 10V |

kilovolt | kV | 1kV = 10^{3}V |
V = 2kV |

megavolt | MV | 1MV = 10^{6}V |
V = 5MV |

**Voltage in series Circuit Connection**

The total voltage of several voltage sources Supply or voltage drops in series is their sum.

*V _{T}* =

*V*

_{1 }+

*V*

_{2 }+

*V*

_{3 }+…

** V_{T}** = the equivalent voltage source or voltage drop in volts (V).

** V_{1}** = voltage source or voltage drop in volts (V).

** V_{2}** = voltage source or voltage drop in volts (V).

** V_{3}** = voltage source or voltage drop in volts (V).

**Voltage in Parallel Circuit Connection**

The total voltage of several voltage sources Supply or voltage in Parallel I have equal Voltage.

*V _{T}* =

*V*

_{1 }=

*V*

_{2 }=

*V*

_{3 }=…

** V_{T}** = the equivalent voltage source or voltage Same or equal in volts (V).

** V_{1}** = voltage source or voltage equal in volts (V).

** V_{2}** = voltage source or voltage equal in volts (V).

** V_{3}** = voltage source or voltage equal in volts (V).

**Voltage Divider Circuit Connection for DC Circuit**

For an Electrical circuit with resistors (or other impedance) in series, the voltage drop V_{i} on resistor R_{i} is:

For a DC circuit with a constant voltage source V_{T} and resistors in series, the voltage drop V_{i} in resistor R_{I} is given by the formula:

**V _{i}** – voltage drop in resistor Ri in volts [V].

**V _{T}** – the equivalent voltage source or voltage drop in volts [V].

**R _{i}** – resistance of resistor R

_{i}in ohms [Ω].

**R _{1}** – resistance of resistor R

_{1}in ohms [Ω].

**R _{2}** – resistance of resistor R

_{2}in ohms [Ω].

**R _{3}** – resistance of resistor R

_{3}in ohms [Ω].

**Voltage Divider Circuit Connection for AC Circuit**

For an AC circuit with voltage source VT and loads in series, the voltage drop Vi in load Zi is given by the formula:

**V _{i}** – voltage drop in load Z

_{i}in volts [V].

**V _{T}** – the equivalent voltage source or voltage drop in volts [V].

**Z _{i}** – impedance of load Z

_{i}in ohms [Ω].

**Z _{1}** – impedance of load Z

_{1}in ohms [Ω].

**Z _{2}** – impedance of load Z

_{2}in ohms [Ω].

**Z _{3}** – impedance of load Z

_{3}in ohms [Ω].

**Kirchhoff’s voltage law (KVL) Circuit Connection**

The sum of the voltage drops at a current loop is zero.

∑ *V _{k}* = 0

**DC Circuit Connection**

Direct current Line (DC) is generated by a constant voltage source like a battery (12V) or DC voltage source.

The voltage drop on a resistor (R) can be calculated from the resistor’s resistance and the resistor’s current, using Ohm’s law:

**Voltage calculation with Ohm’s law**

*V*_{R} = *I*_{R} × *R*

** V_{R}** = voltage drop on the resistor measured in volts (V).

** I_{R}** = current flow through the resistor measured in amperes (A).

** R** = resistance of the resistor measured in ohms (Ω)

**AC Circuit Connection**

An alternating current is generated by a sinusoidal voltage source.

**Ohm’s law**

*V*_{Z} = *I*_{Z} × *Z*

** V_{Z}** = voltage drop on the load measured in volts (V)

** I_{Z}** – current flow through the load measured in amperes (A)

** Z** – impedance of the load measured in ohms (Ω)

**Momentary voltage**

*v*(*t*) = *V _{max}* ×

*sin*(

*ωt*

*+θ*)

**v(t)** = voltage at time t, measured in volts (V).

**V _{max}** = maximal voltage (= amplitude of sine), measured in volts (V).

** ω ** = angular frequency measured in radians per second (rad/s).

**t** = time, measured in seconds (s).

** θ** = phase of sine wave in radians (rad).

**RMS (effective) voltage**

*V _{rms}* =

*V*

_{eff}=

*V*

_{max }/ √2 ≈ 0.707

*V*

_{max}**V _{rms}** = RMS voltage, measured in volts (V).

**V _{max}** = maximal voltage (=amplitude of sine), measured in volts (V).

**Peak-to-peak voltage**

*V _{p-p}* = 2

*V*

_{max}

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**Line Voltage by Country**

AC voltage supply may vary for each country.

Country | Voltage (V) | Frequency (Hz) |
---|---|---|

China | 220V | 50Hz |

Philippines | 220V | 50Hz |

Russia | 220V | 50Hz |

South Africa | 220V | 50Hz |

Thailand | 220V | 50Hz |

France | 230V | 50Hz |

Germany | 230V | 50Hz |

India | 230V | 50Hz |

Ireland | 230V | 50Hz |

Israel | 230V | 50Hz |

Italy | 230V | 50Hz |

New Zealand | 230V | 50Hz |

UK | 230V | 50Hz |

Japan | 100V | 50/60Hz |

Brazil | 110V | 60Hz |

USA | 120V | 60Hz |

Canada | 120V | 60Hz |

**Volts to watts conversion**

The power in watts (W) is equal to the voltage in volts (V) times the current in amps (A):

watts (W) = volts (V) × amps (A)

**Volts to joules conversion**

The energy in joules (J) is equal to the voltage in volts (V) times the electric charge in coulombs (C):

joules (J) = volts (V) × coulombs (C)

**Volts to amps conversion**

The current in amps (A) is equal to the voltage in volts (V) divided by the resistance in ohms (Ω):

amps (A) = volts (V) / ohms(Ω)

The current in amps (A) is equal to the power in watts (W) divided by the voltage in volts (V):

amps (A) = watts (W) / volts (V)

**Volts to electron-volts conversion**

The energy in electronvolts (eV) is equal to the potential difference or voltage in volts (V) times the electric charge in electron charges (e):

electronvolts (eV) = volts (V) × electron-charge (e)

electronvolts (eV) = volts (V) × 1.602176e-19 coulombs (C)

**Voltage Drop Definition**

A Voltage drop is the drop of electrical potential or potential difference in the load in an electrical circuit diagram.

**Voltage Measurement ****Definition**

Electrical voltage is measured with a Voltmeter. The Voltmeter is connected in parallel to the measured component or circuit testing. The voltmeter has very high resistance, so it almost does not affect the measured circuit.

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