Why is voltage e

English Spanish. Enable Cookies. Go Back. Search Delivery. Each unit of measurement is named after a famous experimenter in electricity: The amp after the Frenchman Andre M.

The mathematical symbol for each quantity is meaningful as well. The "R" for resistance and the "V" for voltage are both self-explanatory, whereas "I" for current seems a bit weird. The "I" is thought to have been meant to represent "Intensity" of electron flow , and the other symbol for voltage, "E," stands for "Electromotive force. All of these symbols are expressed using capital letters, except in cases where a quantity especially voltage or current is described in terms of a brief period of time called an "instantaneous" value.

For example, the voltage of a battery, which is stable over a long period of time, will be symbolized with a capital letter "E," while the voltage peak of a lightning strike at the very instant it hits a power line would most likely be symbolized with a lower-case letter "e" or lower-case "v" to designate that value as being at a single moment in time.

This same lower-case convention holds true for current as well, the lower-case letter "i" representing current at some instant in time. Most direct- current DC measurements, however, being stable over time, will be symbolized with capital letters. One foundational unit of electrical measurement, often taught in the beginnings of electronics courses but used infrequently afterwards, is the unit of the coulomb , which is a measure of electric charge proportional to the number of electrons in an imbalanced state.

One coulomb of charge is equal to 6,,,,,, electrons. The symbol for electric charge quantity is the capital letter "Q," with the unit of coulombs abbreviated by the capital letter "C. Cast in these terms, current is the rate of electric charge motion through a conductor. As stated before, voltage is the measure of potential energy per unit charge available to motivate electrons from one point to another.

A useful comparison for these purposes is a simple system containing water such as a water tank with a pipe attached and the water passing through a half open tap. The higher the level of water above the tap, the greater the pressure forcing the water through the pipe and through the half open tap. The greater the water pressure, then the more water that will flow through the system for a given level of resistance in the system.

Similarly with an electrical system, the higher the electric pressure or potential difference across a section of the system, the greater the amount of will pass through the system for a given level of electrical resistance. It can be seen that that raising the pressure of water increases the flow. For an electrical circuit raising the electric potential or voltage increases the current flowing.

When looking at the analogy of the water system as an explanation for potential difference, it is worth remembering that it is only a basic analogy, and there are some fundamental differences between the water tank and an electrical circuit, especially in terms of the fact that the electrical circuit is just that, and the water system is not.

However it serves well to illustrate the concept of pressure and electric potential in a manner that can be understood. The basic unit of voltage is the volt, named after the Italian scientist, Alessandro Volta, who made some early batteries and performed many other experiments with electricity.

The standard unit of voltage or potential difference and electromotive force in the International System of Units SI , is formally defined to be the difference of electric potential between two points of a conductor carrying a constant current of one ampere, when the power dissipated between these points is equal to one watt. To give an idea of the voltages which are likely to be encountered, a CB radio will usually operate from a supply of around 12 volts 12 V.

The cells used in domestic batteries have a voltage of around 1. Rechargeable Nickel Cadmium cells have a slightly smaller voltage of 1. In other areas voltages much smaller and much greater than this can be encountered. The signal input to an audio amplifier will be smaller than this, and the voltages will often be measured in millivolts mV or thousandths of a volt.

Resistance is the amount of opposition to electrical current. This can be likened to the diameter of a pipe resisting the flow of drainage from the bathtub. The larger the pipe lower resistance the faster gravity can pull the water out of the bathtub.

Counters Electron Flow. A greater amount of water will flow when the valve is opened wider; more electrons will flow when there is less resistance.

A lessor amount of water will flow when the valve is more closed; less electrons will flow when the resistance is greater.