Its all about Physics.

  Waves: A wave is a dynamic disturbance that propagates and causes a change in equilibrium of one or more parameters in physics, mathematics, and related subjects. Quantities may oscillate regularly around an equilibrium (resting) value at certain frequency if a wave is periodic. A traveling wave is one in which the entire waveform moves in one direction; in contrast, a standing wave is one in which two periodic waves are overlaid and move in the opposing directions. In a standing wave, there are some points where the wave amplitude seems reduced or even zero, and these positions have null vibration amplitudes. A wave equation (standing wave field comprising two opposing waves) or a one-way wave equation (for single wave propagation in a certain direction) is frequently used to describe waves.   In classical physics, two types of waves are most frequently examined. Stress and strain fields oscillate around a mechanical equilibrium in a mechanical wave. A mechanical wave is a ...

  Light: Introduction: The region of the electromagnetic spectrum that the human eye perceives as light, or visible light, is made up of electromagnetic radiation. Typically, visible light is characterized as having wavelengths between 400 and 700 nanometers (nm), or frequencies between 750 and 420 terahertz, which fall between the longer-wavelength infrared and the shorter-wavelength ultraviolet (with shorter wavelengths).   Light The term "light" in physics can be used to more broadly describe electromagnetic radiation of any wavelength, whether or not it is visible. Gamma rays, X-rays, microwaves, and radio waves are all forms of light in this sense. Intensity, propagation direction, frequency or wavelength spectrum, and polarization are the four main characteristics of light. One of the fundamental constants of nature is its speed in a vacuum, which is 299 792 458 meters per second (m/s). Similar to all other forms of electromagnetic radiation, visible light is propagated...