Each particle in the medium experiences simple harmonic motion in periodic waves by moving back and forth periodically through the same positions.
Consider the simplified water wave in Figure This wave is an up-and-down disturbance of the water surface, characterized by a sine wave pattern. The uppermost position is called the crest and the lowest is the trough. It causes a seagull to move up and down in simple harmonic motion as the wave crests and troughs pass under the bird. Mechanical waves are categorized by their type of motion and fall into any of two categories: transverse or longitudinal.
Note that both transverse and longitudinal waves can be periodic. A transverse wave propagates so that the disturbance is perpendicular to the direction of propagation. An example of a transverse wave is shown in Figure In contrast, in a longitudinal wave , the disturbance is parallel to the direction of propagation. Figure Longitudinal waves are sometimes called compression waves or compressional waves , and transverse waves are sometimes called shear waves.
Transverse and longitudinal waves may be demonstrated in the class using a spring or a toy spring, as shown in the figures. Waves may be transverse, longitudinal, or a combination of the two. The waves on the strings of musical instruments are transverse as shown in Figure Sound waves in air and water are longitudinal.
Their disturbances are periodic variations in pressure that are transmitted in fluids. Sound in solids can be both longitudinal and transverse. Essentially, water waves are also a combination of transverse and longitudinal components, although the simplified water wave illustrated in Figure The longitudinal waves in an earthquake are called pressure or P-waves, and the transverse waves are called shear or S-waves.
These components have important individual characteristics; for example, they propagate at different speeds. Earthquakes also have surface waves that are similar to surface waves on water.
Energy propagates differently in transverse and longitudinal waves. It is important to know the type of the wave in which energy is propagating to understand how it may affect the materials around it. This video explains wave propagation in terms of momentum using an example of a wave moving along a rope. It also covers the differences between transverse and longitudinal waves, and between pulse and periodic waves. Many people enjoy surfing in the ocean. For some surfers, the bigger the wave, the better.
In one area off the coast of central California, waves can reach heights of up to 50 feet in certain times of the year Figure How do waves reach such extreme heights? Other than unusual causes, such as when earthquakes produce tsunami waves, most huge waves are caused simply by interactions between the wind and the surface of the water.
The wind pushes up against the surface of the water and transfers energy to the water in the process. The stronger the wind, the more energy transferred. As waves start to form, a larger surface area becomes in contact with the wind, and even more energy is transferred from the wind to the water, thus creating higher waves. Intense storms create the fastest winds, kicking up massive waves that travel out from the origin of the storm.
Sound waves cannot travel in the vacuum of space because there is no medium to transmit these mechanical waves. Electricity can be static, like the energy that can make your hair stand on end. Magnetism can also be static, as it is in a refrigerator magnet.
A changing magnetic field will induce a changing electric field and vice-versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate. This means that electromagnetic waves can travel not only through air and solid materials, but also through the vacuum of space.
In the 's and 's, a Scottish scientist named James Clerk Maxwell developed a scientific theory to explain electromagnetic waves. He noticed that electrical fields and magnetic fields can couple together to form electromagnetic waves. He summarized this relationship between electricity and magnetism into what are now referred to as "Maxwell's Equations. Heinrich Hertz, a German physicist, applied Maxwell's theories to the production and reception of radio waves. The unit of frequency of a radio wave -- one cycle per second -- is named the hertz, in honor of Heinrich Hertz.
His experiment with radio waves solved two problems. First, he had demonstrated in the concrete, what Maxwell had only theorized — that the velocity of radio waves was equal to the velocity of light!
This proved that radio waves were a form of light! Second, Hertz found out how to make the electric and magnetic fields detach themselves from wires and go free as Maxwell's waves — electromagnetic waves. Light is made of discrete packets of energy called photons.
Photons carry momentum, have no mass, and travel at the speed of light. All light has both particle-like and wave-like properties. How an instrument is designed to sense the light influences which of these properties are observed. An instrument that diffracts light into a spectrum for analysis is an example of observing the wave-like property of light. The particle-like nature of light is observed by detectors used in digital cameras—individual photons liberate electrons that are used for the detection and storage of the image data.
One of the physical properties of light is that it can be polarized. Polarization is a measurement of the electromagnetic field's alignment. In the figure above, the electric field in red is vertically polarized. Think of a throwing a Frisbee at a picket fence. Non-Mechanical waves : It does not require any matter to propagate from one place to another as it consists of photons. This types of waves are also known as an electromagnetic wave.
Electromagnetic waves: The wave which is generated due to vibration between electric field and magnetic field and it does not need any medium to travel is called an electromagnetic wave.
It can travel through a vacuum. Start Learning English Hindi. This question was previously asked in. Win over the concepts of Waves and get a step ahead with the preparations for Physics with Testbook. Start Now.
Concept: A wave can be defined as a disturbance by which energy can be propagated from one place to another without the transport of matter. Waves are of two types: Mechanical Wave: It requires a matter to propagate and these waves are also known as an elastic wave. Two types of mechanical wave are there; Longitudinal : Vibration of particles in a medium and the propagation of the wave in the same direction. Example: Sound waves in air. Transverse: Vibration of particles in a medium and the propagation of wave are perpendicular to each other.
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