m o= omega² a³.

Kepler's first law

A planet orbits the Sun in an ellipse with the Sun at one focus.

Kepler's second law

A ray directed from the Sun to a planet sweeps out equal areas in equal times.

Kepler's third law

The square of the period of a planet's orbit is proportional to the cube of that planet's semimajor axis; the constant of proportionality is the same for all planets.

Kirchhoff's first law

An incandescent solid or gas under high pressure will produce a continuous spectrum.

Kirchhoff's second law

A low-density gas will radiate an emission-line spectrum with an underlying emission continuum.

Kirchhoff's third law

Continuous radiation viewed through a low-density gas will produce an absorption-line spectrum.

loop rule

The sum of the potential differences encountered in a round trip around any closed loop in a circuit is zero.

point rule

The sum of the currents toward a branch point is equal to the sum of the currents away from the same branch point.