What is Voltage?

By R. W. Hurst, President, The Electricity Forum

What is Voltage?

To comprehend the concept of voltage, one must first understand its fundamental principles. Voltage, or electric potential, is the force that drives charge carriers (such as electrons) to move within an electrical circuit. It is analogous to water pressure in a plumbing system, where higher water pressure causes water to flow more quickly through pipes. Similarly, higher voltages encourage the flow of electrons in an electrical circuit.

Italian physicist Alessandro Volta played a crucial role in discovering and understanding V. The unit of voltage, the volt (V), is named in his honor. V is measured in volts, and the process of measuring V typically involves a device called a voltmeter. In an electrical circuit, the V difference between two points determines the energy required to move a charge, specifically one coulomb of charge, between those points.

An electric potential difference between two points produces an electric field, represented by electric lines of flux (Fig. 1). There is always a pole that is relatively positive, with fewer electrons, and one that is relatively negative, with more electrons. The positive pole does not necessarily have a deficiency of electrons compared with neutral objects, and the negative pole might not have a surplus of electrons concerning neutral things. But there's always a difference in charge between the two poles. So the negative pole always has more electrons than the positive pole.



Fig 1. Electric lines of flux always exist near poles of electric charge.


The abbreviation for voltage measurement is V. Sometimes, smaller units are used. For example, the millivolt (mV) is equal to a thousandth (0.001) of a volt. The microvolt (uV) is equal to a millionth (0.000001) of a volt. And it is sometimes necessary to use units much larger than one volt. For example, one kilovolt (kV) is equal to one thousand volts (1,000). One megavolt (MV) is equal to one million volts (1,000,000) or one thousand kilovolts.

The concept of V is closely related to electromotive force (EMF), which is the energy source that drives electrons to flow through a circuit. A chemical battery is a common example of a voltage source that generates EMF. The negatively charged electrons in the battery are compelled to move toward the positive terminal, creating an electric current.

V is a fundamental concept in electrical and electronic systems, as it influences the behavior of circuits and devices. One of the most important relationships involving V is Ohm's Law, which describes the connection between voltage, current, and resistance in an electrical circuit. For example, Ohm's Law states that the V across a resistor is equal to the product of the current flowing through it and the resistance of the resistor.

The voltage dropped across components in a circuit is critical when designing or analyzing electrical systems. Voltage drop occurs when the circuit components, such as resistors, capacitors, and inductors, partially consume the V source's energy. This phenomenon is an essential aspect of circuit analysis, as it helps to determine a system's power distribution and efficiency. Potential energy is defined as the work required to move a unit of charge from different points in an electric dc circuit in a static electric field.

Voltage levels are standardized in both household and industrial applications to ensure electrical equipment's safe and efficient operation. In residential settings, common voltage levels range from 110 to 240 volts, depending on the country. Industrial applications often utilize higher voltages, up to several kilovolts, to transmit electrical energy over long distances with minimal losses.

Another important distinction in the realm of voltage is the difference between alternating current (AC) and direct current (DC)  AC alternates periodically, whereas DC maintains a constant direction. AC is the standard for most household and industrial applications, as it can be easily transformed to different voltage levels and is more efficient for long-distance transmission. DC voltage, on the other hand, is often used in batteries and electronic devices.

Voltage is the driving force behind the flow of charge carriers in electrical circuits. It is essential for understanding the behavior of circuits and the relationship between voltage, current, and resistance, as described by Ohm's Law. The importance of V levels in household and industrial applications and the significance of voltage drop in circuit analysis cannot be overstated. Finally, the distinction between AC and DC voltage is critical for electrical systems' safe and efficient operation in various contexts.

By incorporating these concepts into our understanding of voltage, we gain valuable insight into the world of electricity and electronics. From the pioneering work of Alessandro Volta to the modern applications of voltage in our daily lives, it is clear that voltage will continue to play a crucial role in the development and advancement of technology.

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