# Linear polarization

In electrodynamics, **linear polarization** or **plane polarization** of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation. See polarization for more information.

The orientation of a linearly polarized electromagnetic wave is defined by the direction of the electric field vector.^{[1]} For example, if the electric field vector is vertical (alternately up and down as the wave travels) the radiation is said to be vertically polarized.

## Mathematical description of linear polarization

The classical sinusoidal plane wave solution of the electromagnetic wave equation for the electric and magnetic fields is (cgs units)

for the magnetic field, where k is the wavenumber,

is the angular frequency of the wave, and is the speed of light.

Here

is the amplitude of the field and

is the Jones vector in the x-y plane.

The wave is linearly polarized when the phase angles are equal,

This represents a wave polarized at an angle with respect to the x axis. In that case, the Jones vector can be written

The state vectors for linear polarization in x or y are special cases of this state vector.

If unit vectors are defined such that

and

then the polarization state can written in the "x-y basis" as

## See also

- Sinusoidal plane-wave solutions of the electromagnetic wave equation
- Polarization
- Photon polarization

## References

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