The laws list
R


R to Rydberg formula.


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R.

 R

See ideal gas constant.
 radian; rad

The supplementary SI unit of angular measure, defined as the
central angle of a circle whose subtended arc is equal to the
radius of the circle.
 RayleighJeans law

For a blackbody at thermodynamic temperature T, the radiancy
R over a range of frequencies between nu and nu + dnu
is given by
R = 2 pi nu^{2} k T/c^{2}.
Compare Planck radiation law; see ultraviolet catastrophe.
 Rayleigh criterion; resolving power

A criterion for determining how finely a set of optics may be able to
distinguish. It begins with the assumption that central ring of
one image should fall on the first dark ring of the other; for an
objective lens with diameter d and employing light with
a wavelength lambda (usually taken to be 560 nm),
the resolving power is approximately given by
1.22 lambda/d.
 reflection law

For a wavefront intersecting a reflecting surface, the angle of
incidence is equal to the angle of reflection, in the same plane
defined by the ray of incidence and the normal.
 refraction law

For a wavefront travelling through a boundary between two
media, the first with a refractive index of n_{1}, and
the other with one of n_{2}, the angle of incidence theta
is related to the angle of refraction phi by
n_{1} sin theta = n_{2} sin phi.
 relativity principle

The principle, employed by Einstein's relativity theories, that
the laws of physics are the same, at least qualitatively, in all
frames. That is, there is no frame that is better (or
qualitatively any different) from any other. This principle,
along with the constancy principle, constitute the founding
principles of special relativity.
 resolving power

See Rayleigh criterion.
 righthand rule

A trick for righthanded coordinate systems to determine which way
the cross product of two 3vectors will be directed. There are a
few forms of this rule, and it can be applied in many ways. If u
and v are two vectors which are not parallel, then u cross v is a
vector which is directed in the following manner: Orient your
right hand so that your thumb is perpendicular to the plane
defined by the vectors u and v. If you can curl your fingers in
the direction from vector u to vector v, your thumb will point in
the direction of u cross v. (If it doesn't, the vector is
directed in the opposite direction.) This has immediate
application for determining the orientation of the zaxis basis
unit vector, k, in terms of the x and yaxes' basis unit vectors;
curl your right hand in the direction of i to j, and your thumb
will point in the direction of i cross j = k.
The rule is also applicable in several practical applications,
such as determining which way to turn a screw, etc. There is
also a lefthand rule, which exhibits opposite chirality.
 Roche limit

The position around a massive body where the tidal forces due
to the gravity of the primary equal or exceed the surface
gravity of a given satellite. Inside the Roche limit, such a
satellite will be disrupted by tides.
 Rydberg constant (Rydberg)

A constant which governs the relationship of the spectral line
features of an atom through the Rydberg formula.
For hydrogen, it is approximately 1.097 x 10^{7} m^{1}.
 Rydberg formula (Rydberg)

A formula which describes all of the characteristics of hydrogen's
spectrum, including the Balmer, Lyman, Paschen, Brackett, and
Pfund series.
For the transition between an electron in orbital m to
one in orbital n (or the reverse), the wavelength lambda
involved is given by
1/lambda = R (1/m^{2}  1/n^{2}).

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