Definition of waves – Waves are vibrations that propagate. The ideal form of a wave will follow the sinusoid movement.
In addition to electromagnetic radiation, and perhaps gravitational radiation, which can travel through a vacuum, waves are also present in the medium (which due to deformation can generate spring forces) which can travel and transfer energy from one place to another without causing the particles of the medium to move randomly. permanent; i.e. no mass transfer.
The following is an explanation of the definition of waves. Read more!
Definition of Waves
Based on the explanation above, the notion of a wave can be defined as a propagation symptom of a vibration or disturbance. Understanding Waves will continue to occur if the source of this vibration vibrates continuously. Waves carry energy from one place to another .
A medium is called:
- Linear if the different waves at all given points in the medium can be summed.
- Limited if limited, otherwise it is “infinite”.
- Uniform if the physical characteristics do not change at different points.
- Isotropic if the physical properties are “same” in different directions.
A simple example of a wave, if we tie one end of a rope to a pole, and shake the other end of the rope, many hills and valleys will form on the shaken rope. This is what is called a wave.
In the information age like today, waves play a very important role in human life. One of them is the fetus that is still in the womb can be seen with the naked eye because there are ultrasonic waves.
Other examples can be seen in the following events.
- We can hear music because there are sound waves .
- Kidney stones are destroyed with ultrasonic waves.
- The distance from Venus to Earth can be measured with great precision.
- The state of the bowels of the earth and its contents can be known with the help of seismic waves.
- We can enjoy radio and television because there are radio waves.
- We can communicate with each other by phone and many other things.
In general, waves are divided into groups of waves based on the direction of propagation and wave groups based on the medium of propagation. Based on the direction of propagation, waves can be grouped into longitudinal waves and transverse waves. Based on the medium of propagation, waves are grouped into mechanical waves and electromagnetic waves.
Wave Type
When we throw a stone into a lake or pool of water, circular waves are formed and spread out. Waves will also travel along a string stretched straight across a table if we vibrate one end back and forth . Water waves and waves on the rope are two common examples of mechanical waves.
If a wave propagates to cause motion in the medium in which the wave propagates it is called a mechanical wave . On a mechanical wave , travel Waves in the medium occur due to interactions in the medium. The stronger the interaction in a medium , the wave travel will be faster.
Travel pace the wave depends on the inertial medium where the greater the inertial medium, the slower the wave will travel . In contrast to mechanical waves, electromagnetic waves propagate without the need for an intermediary medium such as radio, microwave, infrared, UV and X-ray waves.
1. Types of Waves Based on the Medium
Based on the discussion above , waves can be divided into two types based on the medium of propagation , namely :
- Mechanical wave _ _, which is a type of wave that requires an intermediate medium in its propagation. Examples are waves on a string, water waves, and sound waves.
- Electromagnetic waves _, which is a type of wave that can propagate even though there is no medium. Based on the frequency, the sequence of electromagnetic waves, namely radio and television waves , microwaves , infrared rays , visible rays , ultraviolet rays , X rays , and gamma rays.
2. Types of Waves Based on the Vibration Direction
Based on the direction of vibration, waves can be divided into two types, namely transverse and longitudinal.
a. Transverse Wave
If we observe a string wave , the pattern that is formed propagates along the rope, while the movement of the rope components (distortions) occurs in a direction perpendicular to the rope. Waves with the direction of vibration perpendicular to the direction of propagation are called transverse waves . For sound waves that are produced due to pressure, the direction of vibration that occurs is in the direction of the wave propagation. An example is sound waves in air.
This wave is generated by periodically applying pressure to one part of the air , so that the air molecules around that area also vibrate . The vibrating molecules strike the molecules around them that are at rest, so the molecules that were initially at rest also vibrate in the same direction. And so on , so that the molecules that are farther apart vibrate. This is the phenomenon of wave propagation. The vibration direction is exactly the same as the wave propagation direction.
Description:
I : wave crest .
II : wave hill .
III : valley wave .
IV : one wave cycle abbreviated by one wave .
V : the length of one wave cycle (the distance between the crest of the wave to the crest of the next wave) abbreviated by the wavelength. VI : wave amplitude = biggest wave deviation.
The phase or phase angle of the wave is the same as the phase of the vibration that caused it. In the picture above, if the phase angle at point A is 0 0 , the phase angle at point B = 90 o , point C = 180 o , point D = 270 o , point E = 360 o , point F = 630 o . As for the magnitude of the phase is as follows.
b. Longitudinal Waves
Waves with the direction of vibration the same as the direction of wave propagation are called longitudinal waves.
In the picture above it appears that the direction of vibration is parallel to the direction of wave propagation. A series of density and strain propagates along the length of the spring. Density is the area when the spring coils approach each other, while strain is the area where the spring coils move away from each other .
While transverse waves have patterns of peaks and valleys, longitudinal waves consist of patterns of density and strain. Wavelength is the distance between successive densities or strains ; _ _ what is meant here is the distance from two points that are the same and successive in density or strain.
One of An example of a longitudinal wave is sound waves in air. Air as a medium for sound wave propagation, contracts and stretches along the direction of air wave propagation. Unlike water waves or string waves, sound waves cannot be seen by us eye.
Properties of Waves
1. Reflection or Reflection of Waves
Of course, friends already understand very well about this reflection, so in general I think we agree. In wave reflection, the law of wave reflection applies :
The angle of incidence of the wave is equal to the angle of reflection of the wave. The incident wave, reflected wave, and normal line lie on the same plane.
2. Refraction Wave
The change in the direction of the wave when the wave enters a new medium causing the wave to move at a different speed is called refraction . In refraction there is a change in the rate of propagation. The wavelength increases or decreases with changes in speed, but there is no change in frequency. This event is shown in the following figure.
In this picture the wave speed in medium m 2 is smaller than medium 1. In this case , the direction of the wave bends so that its propagation is more nearly perpendicular to limit. So, the angle of refraction (θ 2 ) , is smaller than the angle of incidence ( θ 1 ), so the Snell’s Law equation is obtained as follows.
or
or
Snell’s law can be used to calculate the angle of incidence or the angle of refraction, and in experiments to calculate the refractive index of a material.
In 1637, René Descartes independently used the heuristic argument of the conservation of momentum in the sine form in his Discourse on Method to explain this law. Light is said to have a higher speed in a denser medium because light is a wave that arises as a result of the disturbances of the plenum , the continuous substance that makes up the universe. In French, Snell’s law is called la loi de Descartes or loi de Snell-Descartes .
Previously, between 100 and 170 AD Ptolemy of Thebaid found an empirical relation of the angle of refraction which was only accurate at small angles. The concept of Snell’s law was first described with mathematical accuracy in 984 by Ibn Sahl of Baghdad in his manuscript On Burning Mirrors and Lenses .
With this concept, Ibn Sahl was able to create lenses that could focus light without geometric aberrations, known as aspherical lenses. The Ibn Sahl manuscript was discovered by Thomas Harriot in 1602, but was not published although he worked with Johannes Kepler in this area.
In 1678, in Traité de la Lumiere , Christiaan Huygens explained Snell’s law from the derivation of Huygens’ principle of the wave nature of light. Snell’s law is said to apply only to isotropic or “regular” mediums under conditions of monochromatic light which only has a single frequency, so it is reversible.
Snell’s law is translated into ratios as follows
3. Mixture (Interference) Waves
Wave fusion occurs when there are waves with different frequencies and phases that meet each other. There will be two results of wave interference, namely constructive (mutually reinforcing) and destructive (mutually weakening). Constructive interference occurs when two waves meet on the same phase, whereas destructive interference occurs when two waves meet on opposite phases.
4. Deflection (Diffraction) Waves
Wave diffraction is the deflection or scattering of waves when they pass through a gap. Diffraction symptoms will become more obvious if the gap is narrower.
5. Wave Dispersion
Wave dispersion is the event of the decomposition of light rays which are a mixture of several wavelengths into their components due to refraction . Dispersion occurs because of the difference in deviation for each wavelength, which is caused by the difference in the speed of each wave when it passes through the refracting medium. If a ray of white light falls on one side of the prism, that white light will unravel into its components and the full spectrum of visible light is visible .
6. Wave Dispolarization
Wave dispolarization is the absorption of part of the direction of the wave vibration , so that it only has one direction. Polarization will only occur in transverse waves, because the wave direction matches the polarization direction, and vice versa, it will be absorbed if the wave direction does not match the polarization direction of the gap.
Utilization of Waves
There are so many uses of waves taking into account the various characteristics of the waves that are around us. Some of them include:
- TV and radio waves for communication.
- Microwaves are used to cook food or what we know as microwaves .
- Sound waves that are very helpful in the health sector , namely ultrasound on ultrasound equipment to check for the presence or absence of disease.
Wave Magnitude
The magnitudes of the waves include:
1. Wavelength
When you observe waves on the surface of the water, then drop a rock on the surface of the water, that’s where peaks and valleys will be seen which are called the wavelength, which is the distance between two adjacent peaks or the distance between two adjacent valleys.
2. Fast Propagation of Waves
Fast wave propagation to see how fast the waves move from one place to another.
3. Deviation
As long as the wave propagates, the deviation in a medium is always changing , starting from its minimum value to its maximum value. The maximum and minimum values are obtained periodically.
4. Amplitude
Amplitude is a non-negative scalar measurement of the magnitude of the oscillation of a wave. Amplitude can also be defined as the farthest distance or deviation from the equilibrium point in sinusoidal waves that we study in physics and mathematics – geometric subjects. The amplitude in the international system is usually symbolized by (A) and has units of meters (m).
5. Period
The period is the oscillation time needed by an object to return to its original oscillation. Suppose a point is at zero deviation .
6. Frequency
Frequency is the number of oscillations per second in a medium. To calculate frequency, one sets the time interval, counts the number of times the event occurs, and divides this count by the length of the time interval. In the International System of Units, the results of this calculation are expressed in units of hertz (Hz), which is the name of a German physicist named Heinrich Rudolf Hertz who discovered this phenomenon for the first time. A frequency of 1 Hz denotes an event that occurs once per second.
where f is the frequency (hertz) and T the period (seconds or seconds).
In addition, the frequency is also related to the number of vibrations with the formula:-
In rotating mechanical devices, the measurement of vibration frequency per minute, abbreviated r/min or rpm, is often used. 60 rpm is equal to one hertz.
7. Oscillation Speed
Oscillations are periodic variations over time of a measurement result, for example a pendulum swing. The term vibration or vibration is often used synonymously with oscillation, although vibration actually refers to a specific type of oscillation, namely mechanical oscillation.
Oscillations do not only occur in a physical system, but also in biological systems and even in society. Oscillations are divided into two types, namely simple harmonic oscillations and complex harmonic oscillations. In simple harmonic oscillations there is simple harmonic motion, which can occur in an object, molecule, or atom.
For other terms in the results of electrical measurements, oscillations can be called flickers or disturbances that change the shape of the wave to be damaged/defective.
Oscillation speed to find out how fast there is a change in deviation in the medium. In transverse waves , the speed of oscillation is seen up and down the deviation, while for longitudinal waves , the speed of oscillation is seen from the fast vibration back and forth.
So, that’s a review of the meaning of waves and a complete explanation behind it.