| The laws list: R |
The laws list R
R to Rydberg formula.
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R.
- 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.
-
- Rayleigh-Jeans 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 nu2
k T/c2.
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 n1,
and the other with one of n2, the angle of incidence
theta is related to the angle of refraction phi by
n1 sin theta = n2
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.
-
- right-hand rule
-
- A trick for right-handed coordinate systems to
determine which way the cross product of two 3-vectors 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 z-axis basis unit vector, k, in terms of
the x- and y-axes' 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
left-hand 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 107
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/m2 - 1/n2).
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