# concepts

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## Permeability (electromagnetism)

In electromagnetism , permeability is the measure of the ability of a material to support the formation of a magnetic field within itself.

## Magnetic monopole

It is impossible to make magnetic monopoles from a bar magnet . If a bar magnet is cut in half, it is not the case that one half has the north pole and the other half has the south pole.

## Magnetic flux

In physics , specifically electromagnetism , the magnetic flux (often denoted Φ or Φ B ) through a surface is the component of the magnetic B field passing through that surface.
Magnetic field of an ideal cylindrical magnet with its axis of symmetry inside the image plane.

## Gaussian surface

A cylindrical Gaussian surface is commonly used to calculate the electric charge of an infinitely long, straight, 'ideal' wire. A Gaussian surface is a closed surface in three dimensional space through which the flux of a vector field is calculated; usually the gravitational field , the electric field, or magnetic field. [ 1 ] It is an arbitrary closed surface S = ∂V V used in conjunction with Gauss's law for the corresponding field ( Gauss' law for gravity , Gauss' law for electricity , or Gauss' law for magnetism ) by performing a surface integral , in order to calculate the total amount of the source quantity enclosed, i.e. amount of gravitational mass as the source of the gravitational field or amount of electric charge as the source of the electrostatic field, or vice versa: calculate the fields for the source distribution. For concreteness, the electric field is considered in this article, as this is the most frequent type of field the surface concept is used for.
The electromagnetic waves that compose electromagnetic radiation can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized EMR wave propagating from left to right.

Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field .

## Electromagnetic induction

An electromagnetic field (also EMF or EM field ) is a physical field produced by electrically charged objects . It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction .

## Electromagnetic field

The electrical resistance of an electrical conductor is the opposition to the passage of an electric current through that conductor; the inverse quantity is electrical conductance , the ease at which an electric current passes.

## Permittivity

A dielectric medium showing orientation of charged particles creating polarization effects.
Electric field lines emanating from a point positive electric charge suspended over a negatively charged infinite sheet An electric field surrounds electrically charged particles and time-varying magnetic fields .

## Electrical conductivity

Electrical resistivity (also known as resistivity , specific electrical resistance , or volume resistivity ) quantifies how strongly a given material opposes the flow of electric current . A low resistivity indicates a material that readily allows the movement of electric charge . Resistivity is commonly represented by the Greek letter ρ ( rho ).
A simple electric circuit, where current is represented by the letter i . The relationship between the voltage (V), resistance (R), and current (I) is V=IR; this is known as Ohm's Law .

## Electric charge

Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter.

## Capacitance

Capacitance is the ability of a body to store an electrical charge . Any object that can be electrically charged exhibits capacitance.