wavelengths of light that are perceived by the human eye, are in the range of 380 to 780 nanometers.These waves travel at a constant speed of approximately 300,000 km / s.Light has wave-particle duality, and its properties are depending on the experiment.

## wave nature of light

light as any electromagnetic wave is described by Maxwell's equations.These include vector equation of E (electric field of the light wave) and H (magnetic field).Voltage vectors are perpendicular to each other.Also they are both perpendicular to the direction of wave propagation, which is given by the velocity vector V.

vector E is the light vector.It was his fluctuations influence the polarization of the light wave.This phenomenon is characteristic only for transverse waves.If the propagation of the light wave vecto
r E retains its initial orientation, such a wave is said to be linearly polarized.Light from the sun or a light bulb is characterized by constant change in the orientation of this vector is called natural (unpolarized).

interference - is the imposition of the light waves, resulting in an amplification or attenuation of the amplitude of the oscillations.Amplification occurs when the path difference of the light waves is an even number of half wavelengths.Weakening can occur if the path difference is an odd number of half wavelengths.To obtain the distribution of intensity maxima and minima are required coherent source.Their difference in phase and frequency of the radiation must be the same.

Diffraction - a bending of light barriers, which are comparable in size to the wavelength of the incident radiation.Diffraction is associated with interference.If light waves which deviate from the forward direction, and come to a point on the screen in the same phase, will experience interference maximum.In a different phase - at least.The phenomenon of diffraction is widely used for various experiments in astrophysics.

## corpuscular nature of light

According to the model developed in the 20th century, the light is a stream of particles (corpuscles).This model is a good description of some of the phenomena that have remained unclear in the framework of the wave nature of light.

photoelectric effect - one of them.The light falling on the surface of the metal, electrons are knocked out of her.This phenomenon was discovered by H. Hertz and studied in detail by the Russian scientist AGStoletov, which found that the number of electrons ejected from the metal surface depends on the intensity of incident light.