Electric field

In physics, an electric field or E-field is an effect produced by an electric charge that exerts a force on charged objects in its vicinity. The units of the electric field are newtons per coulomb or volts per meter (both are equivalent). Electric fields are composed of photons and contain electrical energy with energy density proportional to the square of the field intensity. In the static case, an electric field is composed of virtual photons being exchanged by the charged particle(s) creating the field. In the dynamic case the electric field is accompanied by a magnetic field, by a flow of energy, and by real photons.

Parallels between electrostatics and gravity

As explained above, electric field can be thought of as a proportionality constant when the force exerted on a test charge is proportional to the magnitude of the test charge. Put more simply, this is to say that an environment can be electrostatically quantified by the electric field in that environment; different physical facts of the environment combine to form this single number, and it is possible for different environments to have the same number for electric field. Any given object (that we are measuring the force on) has associated various "weights;" the electrostatic weight is the charge, and the gravitic weight is the mass. The electrostatic force on some object in the environment is then simply the strength of the environment (the electric field), times the magnitude of the electrostatic weight (the charge). This is similar to gravity, where any given environment has a gravitational acceleration, and the force on some object in that environment is simply the acceleration due to gravity (the environmental factor) times the mass of the object (the gravitic weight). For electrostatics, the factors that determine the electric field in an environment are:

Related Topics:
Mass - Acceleration

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• The magnitude of the nearby charge
• The square of the distance between that charge and the object being measured, and
• Coulomb's constant.

The analogous factors for gravity are:

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• The mass of the nearby object
• The square of the distance between that object and the object being measured, and
• The Universal Gravitational Constant.

When measuring the force on a mass at sea level due to Earth's gravity, the first factor (mass of the nearby environment-determining object) is the mass of the Earth, while the second factor (square of the distance between the environment-determining object and the measured object) is the square of the Earth's radius.

Related Topics:
Earth - Radius

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The units of the electric field, Newtons per Coulomb, can thusly by expressed as force per unit charge. It is interesting to note that upon applying the same to principle to a gravitic field (giving such a field units of Newtons per kilogram) and simplifying units, we are left with meters per second squared, or acceleration. This is the very same acceleration as what is known as Earth's gravitational acceleration.

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