Wave Speed
The Speed At Which A Wave Travels, Equal To Wavelength Times Frequency.

Length Contraction
A Phenomenon In Special Relativity In Which Moving Objects Appear Shortened Along The Direction Of Motion.

Standing Wave
A Wave Pattern Formed By The Interference Of Two Waves Traveling In Opposite Directions.

Inertial Frame
A Frame Of Reference In Which Objects Not Subject To Forces Move At Constant Velocity.

Noninertial Frame
A Frame Of Reference That Is Accelerating, Requiring The Use Of Fictitious Forces To Describe Motion.

Fictitious Force
An Apparent Force Experienced In A Noninertial Frame, Such As Centrifugal Force.

Energy Level
A Quantized State In Which An Electron Can Exist In An Atom, Related To Electron Orbitals.

Ground State
The Lowest Energy Level Of An Electron In An Atom.

Excited State
A Higher Energy Level Occupied By An Electron After Absorbing Energy.

Ionization Energy
The Amount Of Energy Required To Remove An Electron From An Atom, Related To Quantum Mechanics.