body vibrating in an elastic medium, creates a disturbance that is transmitted from one point to another and is called a wave.This occurs at a certain rate, which is considered its propagation velocity.That is a value that characterizes the distance traveled by any point of the wave per unit length of time.
Let the wave moves along one axis (eg, horizontal).Its shape is repeated in the space over time, t. E. The wave profile moves along the propagation axis with a velocity having a constant value.During the corresponding period of the oscillation, its front will move a distance called the wavelength.
turns wavelength - the same distance, which "runs" its front for the length of time equal to the period of oscillation.To visualize the wave in the form in which it is usually depicted in the drawings.We all remember how to look, for example, the waves of the sea.Wind drives them along the sea, and each wave has a crest (the maximum point), and the lowest point (at least), and those and others are constantly moving and follow each other.The points in one phase, - the vertices of two adjacent crests (we will assume that the ridges have the same height and the motion is at a constant speed), or the two lowest points of adjacent waves.Wavelength - is precisely the distance between such points (two adjacent ridges).
in the form of waves can propagate all forms of energy - heat, light, sound.They all have different lengths.For example, passing through the atmosphere, the sound waves slightly change air pressure.The areas of maximum pressure maxima correspond to sound waves.Due to its structure the human ear detects these pressure changes and sends signals to the brain.Thus we hear the sound.
length of the sound wave determines its properties.To find it, you need to wave speed (measured in m / sec) divided by the frequency in Hz.Example: at a frequency of 688 Hz sound wave is moving at a speed of 344 m / s.Wherein the wavelength is equal to 344: 688 = 0.5 m. It is known that the propagation velocity of waves in the same environment does not change, therefore, its length will depend on the frequency.Low-frequency sound waves have a wavelength longer than high.
Examples of other varieties of electromagnetic radiation can serve as a light wave.The light - part of the electromagnetic spectrum visible to the eye.Wavelength of light that the human eye can perceive is in the range from 400 to 700 nm (nanometers).On either side of the visible range of the spectrum lie the field does not perceive our eye.
ultraviolet waves have a length less than the length of the visible spectrum.While the human eye is unable to see them, but, nevertheless, they can cause great harm to our eyesight.
wavelength of infrared radiation greater than the maximum length, which we are able to see.These waves are caught by special equipment and are used, for example, a night vision camera.
Among the rays that are available to our vision, the smallest length of the beam has a purple color, the largest - red.Between them lies the entire available spectrum view (remember the rainbow!)
How do we perceive color?Rays of light having a specified length to fall on the retina, having a light-sensitive receptors.These receptors transmit signals directly to our brain, where a particular color sensation.Which color we see - depending on the wavelength of the incident beam, and the brightness of the color is determined by the intensity of the radiation feeling.
All objects around us, have the ability to reflect, transmit or absorb incident light (fully or partly).For example, green leaves means that the whole range of the reflected rays is mainly green, and the rest are absorbed.Transparent objects tend to delay radiation of a certain length, which is used, for example, in photography (using photo filters).
Thus, the color of an object tells us the ability to reflect waves of a certain part of the spectrum.Objects that reflect the entire spectrum, we see white, absorbing all rays - black.
