Know the meaning of Symbols

In Electronics, standard symbols are used to represent Volt, Current, Resistance, Power etc. These standard symbols are seen in electronics theory as well as in circuit diagrams. See the purpose of its use and the variations in representations.

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Volt is the potential difference between two points and is represented using the symbol V or E. This symbol was given after the famous Italian experimenter in electricity, the AlessandroVolta. If the symbol for volt is represented as E, it stands for the “Electromotive force”. The symbols E and V are interchangeable but some authors use the symbol E to represent the voltage of battery and V for other power sources. Generally the symbol for volt E or V is representing in the capital letters while the small letter e or v is used for the voltage of a short period. For example, the voltage across the battery or mains is represented as E or V while the high voltage in the power line or lightning strike for the short period is represented as e or v. The term Voltage is the potential energy available to motivate the flow of electrons through a conductor.


Current is the continuous flow of free electrons through a conductor. It is measured in terms of Ampere. The term was introduced after the famous French scientist Andre.M.Ampere. Current is represented using the symbol I which shows the Intensity of electron flow. Like volt, current from the sources like battery is expressed using capital letter I and the current at an instant time is represented as i.


Resistance is the opposing force offered by the conductor to restrict the flow of current. Resistance is represented using the symbol Ω and measured in terms of Ohms, Kilo Ohms and Mega Ohms. 1000 Ohms is 1 Kilo Ohm. The symbol ohm is difficult to represent in circuit diagram so instead of Ω, the letter R is used in circuit diagrams to show the value of resistor below 1K. E.g. 100 R means 100 Ohms.

Electric charge

Coulomb is the fundamental unit of electrical measurement. It is defined as the measurement of electric charge proportional to the number of electrons in the imbalanced state. One Coulomb is equal to 6,250,000,000,000,000,000 electrons. Electric charge is represented using the symbol Q but the unit of Coulomb is represented using the capital letter C. There is a relationship between the Ampere and Coulomb. 1 Ampere is equal to 1 Coulomb of electrons passing through a point in 1 second.


The term Energy is widely used in electronics and is the potential energy measured in terms of Joule. One Joule is proportional to the amount of work performed by a force of one Newton exerted through a motion of one meter in the same direction. Volt and Joule are related. One volt is equal to one Joule of electrical energy per one Coulomb charge. Thus a 12 volt battery can give 12 Joules of energy for every Coulomb of electrons.