Frequency and wavelength converter. Light wavelengths How wavelength is determined

Light wave – electromagnetic wave in the visible wavelength range. The frequency of the light wave determines the color. The energy transferred by a light wave is proportional to the square of its amplitude.

Light waves cover a huge range on the electromagnetic wave scale, beyond ultra-short millimeter radio waves and extending to the shortest gamma rays - electromagnetic waves with a wavelength ʎ less than 0.1 nm (1 nm = 10 -9 m)

Every wave propagates from one point to another not instantly, but at a certain speed.

The speed of propagation of light and electromagnetic waves in general in a vacuum (and practically in air) is approximately 300,000 km/s

Near an object, its shadow has sharp edges, but the outline
shadows blur as distance between objects increases
and shadow. This is not difficult to understand if we consider that light travels
is rectilinear, and each light source has finite
sizes. The study of the propagation of light rays shows
that at the edge of each shadow there is a partially illuminated area
lust. This so-called penumbra makes the outline of the shadow different
washed. The darkest part of the shadow (deep shadow) is completely
fenced off from the light source. The width of the penumbra is smaller
the closer the shadow is to the object that casts it, so
Close to the object, the shadow appears sharper.

It was found that a light wave is an oscillation of electric and magnetic fields propagating in space; both fields oscillate in mutually perpendicular planes, which are also perpendicular to the direction of wave propagation. In fact, light waves are a type of electromagnetic wave, which also includes x-rays, ultraviolet, infrared, and radio waves. Light waves are emitted by atoms when electrons in them move from one orbit to another. If an atom receives energy, such as in the form of heat, light, or electrical energy, electrons move away from the nucleus into higher-energy orbits. They then move back to orbits closer to the nucleus with lower energy, while emitting energy in the form of electromagnetic waves. This is how light arises.

Waveform- a visual representation or an abstract representation of a waveform, such as a wave, propagating through a physical medium.

In many cases, the medium in which the wave propagates does not allow its shape to be observed visually. In this case, the term "signal" refers to the graph form of a quantity as a function of time or distance. To visualize the waveform, a tool called an oscilloscope can be used to display the value of the measured quantity and its change on the screen. In a broader sense, the term "signal" is used to refer to the shape of a graph of the values ​​of any quantity that changes over time.

Common periodic signals are ( t- time):

Sine wave: sin (2 π t). The signal amplitude corresponds to a trigonometric sine function (sin) varying over time.

· Meander: saw( t) − saw ( t− duty). This signal is typically used to represent and transmit digital data. Rectangular pulses with a constant period contain odd harmonics that fall at −6 dB/octave.

· Triangular wave: ( t− 2 floor (( t+ 1) /2)) (−1) floor (( t+ 1) /2) . Includes odd harmonics that fall at −12 dB/octave.

Sawtooth wave: 2 ( t− floor( t)) − 1. Looks like saw teeth. Used as a starting point for subtractive synthesis, since the constant-period sawtooth wave contains even and odd harmonics that fall at −6 dB/octave.

Other waveforms are often called composite waveforms because in most cases they can be described as a combination of several sine waves or the sum of other basis functions.

The Fourier series describes the decomposition of a periodic signal based on the fundamental principle that any periodic signal can be represented as a sum (possibly infinite) of fundamental and harmonic components. Energy-finite non-periodic signals can be analyzed as sinusoids after a Fourier transform.

Wavelength (λ) is the shortest distance between wave points oscillating in the same phases. We perceive light with our eyes. It is an electromagnetic wave with a wavelength (in vacuum) from 760 nm (red) to 420 nm (violet). - wavelength. The frequency of light vibrations is from 4. 10 14 Hz (purple) to 7 . 10 14 Hz (red). This is a fairly narrow strip on the scale of electromagnetic waves. The frequency of the light wave (wavelength in a vacuum) determines the color of the light we see: A sine wave symbolically shows the frequency (wavelength) of the corresponding part of the spectrum (color). The main spectral colors (which have their own names), as well as the emission characteristics of these colors, are presented in the table:	λ - light wavelength	m
c - speed of light	m/c
T - period of EM oscillations	With
ν - frequency of light wave oscillations	Hz

Oscillations- a process of changing the states of a system around the equilibrium point that is repeated to one degree or another over time. For example, when a pendulum oscillates, its deviations in one direction or another from the vertical position are repeated; When oscillations occur in the electrical oscillatory circuit, the magnitude and direction of the current flowing through the coil are repeated.

Electromagnetic vibrations are called periodic changes in tension E and induction B.

Electromagnetic waves include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma rays.

The transmission of vibrations is due to the fact that adjacent areas of the medium are connected to each other. This connection can be carried out in different ways. It may be due, in particular, , elastic forces, arising as a result of deformation of the medium during its vibrations. As a result, an oscillation caused in some way in one place entails the successive occurrence of oscillations in other places, more and more distant from the original one, and the so-called wave.

Electromagnetic waves - these waves represent the transmission from one place in space to another of oscillations of electric and magnetic fields created by electric charges and currents. Any change in the electric field causes the appearance of a magnetic field, and vice versa, any change in the magnetic field creates an electric field. A solid, liquid or gaseous medium can greatly influence the propagation of electromagnetic waves, but the presence of such a medium is not necessary for these waves. Electromagnetic waves can propagate wherever an electromagnetic field can exist, and therefore in a vacuum, i.e. in a space containing no atoms.

Every wave propagates from one point to another not instantly, but at a certain speed.

Electromagnetic oscillations are interconnected oscillations of electric and magnetic fields.

Electromagnetic vibrations appear in various electrical circuits. In this case, the amount of charge, voltage, current strength, electric field strength, magnetic field induction and other electrodynamic quantities fluctuate.

Free electromagnetic oscillations arise in an electromagnetic system after removing it from a state of equilibrium, for example, by imparting a charge to a capacitor or changing the current in a section of the circuit.

These are damped oscillations, since the energy imparted to the system is spent on heating and other processes.

Forced electromagnetic oscillations are undamped oscillations in a circuit caused by an external periodically changing sinusoidal EMF.

Electromagnetic oscillations are described by the same laws as mechanical ones, although the physical nature of these oscillations is completely different.

Electrical vibrations are a special case of electromagnetic ones, when vibrations of only electrical quantities are considered. In this case, they talk about alternating current, voltage, power, etc.

OSCILLATION CIRCUIT

An oscillatory circuit is an electrical circuit consisting of a capacitor with capacitance C, a coil with inductance L and a resistor with resistance R connected in series.

The state of stable equilibrium of the oscillatory circuit is characterized by the minimum energy of the electric field (the capacitor is not charged) and the magnetic field (there is no current through the coil).

Quantities expressing the properties of the system itself (system parameters): L and m, 1/C and k

quantities characterizing the state of the system:

quantities expressing the rate of change in the state of the system: u = x"(t) And i = q"(t).

Wavelength

Examples

Approximately, with an error of about 0.07%, you can calculate the radio wavelength as follows: 300 divided by the frequency in megahertz, we get the wavelength in meters, for example for 80 Hz, the wavelength is 3750 kilometers, for 89 MHz - 3.37 meters, for 2 .4 GHz - 12.5 cm.

The exact formula for calculating the wavelength of electromagnetic radiation in a vacuum is:

where is the speed of light, equal in the International System of Units (SI) to 299,792,458 m/s exactly.

To determine the wavelength of electromagnetic radiation in any medium, use the formula:

where is the refractive index of the medium for radiation with a given frequency.

Notes

Literature

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See what “Wavelength” is in other dictionaries:

The distance between the two closest points of a harmonic wave that are in the same phase. Wavelength λ = vT, where T is the oscillation period, ? phase velocity of the wave. * * * WAVELENGTH WAVELENGTH, the distance between the two nearest points... ... encyclopedic Dictionary

wavelength- (λ) The distance by which the surface of an equal phase wave moves during one period of oscillation. [GOST 7601 78] wavelength The distance traveled by an elastic wave in a time equal to one full period of oscillation. )