## Electrical Voltage

From the explanation before, in order to move the electron from one point to another, we need some work or energy transfer. This work is happened by electromotive force (emf) externally, and also represented the battery illustration in the principle of electrical circuit.

This emf can be called by

This emf can be called by

*voltage*or*potential difference*. In an electric circuit, voltage*v*in between points_{ab}*a*and*b*is needed to move an unit charge from*a*to*b*as energy or work, in mathematic equation :(1) |

where :

w = work (joules = J)

q = charge (coulombs = C)

The voltage

*v*is measured in volts (V), to respect the physicist inventor, Alessandro Antonio Volta (1745 - 1827), the inventor of first voltaic battery. From Equation.(1) :_{ab}**1 volt = 1 joule/coulomb = 1 newton-meter/coulomb**

Hence,

Voltage or potential difference is required energy to move a unit charge through an elements, measured in volts (V).

Figure 1. Potential difference |

*a*and

*b*. The symbol plus (+) and minus(-) represent the current flow direction or voltage polarity. There are two ways to treat

*v*: (1) potential at point

_{ab}*a*is higher than point

*b*, or (2) potential at point

*a*with respect to point

*b*is

*v*. Logically in general :

_{ab}
For better understanding, here we review Figure.(2). Two representations of same voltage at 9 V has different polarity based on the polarity symbol. In Figure.(2a), point

*a*is +9V above point*b*, while Figure.(2b), point*b*is -9V above point*a*. From this perspective, we can conclude that in Figure.(2a) there is 9V voltage drop from*a*to*b*, and in Figure.(2b) there is 9V voltage rise from*b*to*a*. In other words, the voltage drop in Figure.(2a) is equivalent with voltage rise in Figure.(2b).Figure 2. Voltage polarity |

Like current, voltage also has its form depending on its value in a period of time. The constant value of voltage is known as

Along with electrical current, these two can be used for the calculation of electric power.

Untuk Bahasa Indonesia baca Tegangan Listrik.

*dc voltage*(represented by*V*) and the dynamic one is*ac voltage*(represented by*v*).Along with electrical current, these two can be used for the calculation of electric power.

Untuk Bahasa Indonesia baca Tegangan Listrik.

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