Radius of dark Newton's ring formula
====================================

Newton's rings are annular interference maxima and minima that appear around the point of contact between a convex
lens and a plane—parallel plate when light passes through the lens and plate. When the difference in the path of
the beam reflected from the convex surface of the lens at the glass-air boundary and the beam reflected from the
plate at the air-glass boundary is equal to an entire wave, then these two waves hit the observation point with
the same faces and demonstrate interference.

**Links:**

#. `Wikipedia (ru), last formula in paragraph <https://ru.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BB%D1%8C%D1%86%D0%B0_%D0%9D%D1%8C%D1%8E%D1%82%D0%BE%D0%BD%D0%B0>`__.

..
    TODO rename file
    TODO find English link

.. py:currentmodule:: symplyphysics.laws.optics.radius_dark_newton_ring_from_wavelength_order_radius_curvature_refractive_index

.. py:data:: radius

    :attr:`~symplyphysics.symbols.classical_mechanics.radius` of the dark Newton's ring.

Symbol:
    :code:`r`

Latex:
    :math:`r`

Dimension:
    :code:`length`


.. py:data:: wavelength

    :attr:`~symplyphysics.symbols.classical_mechanics.wavelength`.

Symbol:
    :code:`lambda`

Latex:
    :math:`\lambda`

Dimension:
    :code:`length`


.. py:data:: ring_order

    Ring's order. See :attr:`~symplyphysics.symbols.basic.positive_number`.

Symbol:
    :code:`N`

Latex:
    :math:`N`

Dimension:
    :code:`dimensionless`


.. py:data:: lens_radius_of_curvature

    Lens :attr:`~symplyphysics.symbols.basic.radius_of_curvature`.

Symbol:
    :code:`R`

Latex:
    :math:`R`

Dimension:
    :code:`length`


.. py:data:: medium_refractive_index

    :attr:`~symplyphysics.symbols.optics.relative_refractive_index` of the medium between the lens and the plate.

Symbol:
    :code:`n`

Latex:
    :math:`n`

Dimension:
    :code:`dimensionless`


.. py:data:: law

    :code:`r = sqrt(N * R * lambda / n)`


    Latex:
        .. math::
            r = \sqrt{\frac{N R \lambda}{n}}