Waves
Waves are OSCILLATIONS that carry energy. Waves can move through matter or VACUUMS. Waves that move through matter are called MECHANICAL WAVES, and waves that move through vacuums are called ELECTROMAGNETIC WAVES.
Oscillation: An up-and-down or back-and-forth motion
Vacuums: Space that has no matter in it. (Keep in mind that a vacuum cleaner sucks all material out of space.)
Two examples of mechanical waves:
1. Waves in water created from the back of a speedboat. The energy travels from water molecules to water molecule, making ripples.
2. Taking creates sound waves, which travel by transferring vibrations from molecule to molecule and move the sound from mouth to ear.
Waves Properties
The four main characteristics of a wave are:
- AMPLITUDE is one-half the distance between a waves high point, or CREST, and low point, or TROUGH. Amplitude measures how much a wave is displaced from its resting point. More energetic waves have larger amplitudes. Just think of the ocean waves: Waves that carry more energy are higher and farther away from the normal waterline, so they have a larger amplitude.
- Wavelengh is measured from a point on one wave to the same point on the next wave-like crest-to-crest or trough-to-trough- and is written as λ. The difference between colors is caused by different wavelength of light. The wavelength of red is longer than that of blue.
- Frequency: The number of waves that pass a fixed point in a given unit of time is called FREQUENCY, written as f. The unit for frequency is a hertz (Hz), which is the number of waves per second. Frequency and wavelength are inversely proportional if the waves are traveling the same speed, meaning: When frequency is higher, wavelength must be smaller (and vice versa).
In the first situation, ten waves must go through in the same amount of time, which requires two waves! since the waves travel at the same speed, the ten waves must be closer together (shorter wavelengths)
- Wave Speed: The time it takes for a wave to move from one point to another is called the wave velocity, which is represented in equations by V (for velocity).. The equation for wave speed is:
wave speed = frequency x wavelength
(abbreviated as v = f x λ)
Wave speed is measured in meters per second (m/s), frequency is measured in hertz (Hz), and wavelength is measured in meters (m).
Waves travel at different speeds in different mediums. For example: Mechanical waves, such as sound waves, such as sound waves, travel faster in water than they do in air. Electromagnetic waves, such as light, are the opposite: They travel faster in air than they do in water. When you put a pencil into a glass of water, the pencil appears distorted because the light waves reflected from the pencil travel faster in the air than under water.
Wave Behavior
Reflection is when a wave bounces off a surface. When you look in the mirror, you see yourself because the light waves are reflected from the mirror.
The Law of Reflection explains that waves are reflected in a certain way – the wave is reflected at the same angle as the angle it moved towards the obstacle. So, if a wave moves toward a wall at 90 degrees, it will also bounce off at 90 degrees.
The Bending of waves as they travel through different mediums (like the distorted light waves of a pencil in a cup of water) is called Refraction and is caused by waves traveling at different speeds in different mediums (or substances).
That’s why your legs sometimes seem very short when you’re standing in the pool!
Diffraction is the bending of waves around an obstacle or the propagation of waves near small openings.. You can see diffraction when ocean waves come through a jetty or pier.
The result of waves colliding with each other is called Interference. When waves collide, they either combine to form a larger wave, a process called Constructive Interference, or they interfere with each other and cancel each other out, a process called destructive interference. When you jump on a trampoline with friends, you experience constructive and destructive interference. When you jump at just the right time, you get launched into the air! Other times, you hardly move. And sometimes the interference is somewhere in between constructive and destructive.
Characteristics Of Sound and Light Waves
Light and sound waves have different characteristics. Sound wave transfer energy from one source to another, while light wave only transmit energy. Sound cannot pass through some substances such as lead. Thus, sound cannot be transmitted through electromagnetic radiation.
To see in the infrared and ultraviolet light, our eyes must convert light into heat. The human eye consists of many tiny capillaries that supply an image to the brain when light is absorbed. All objects consist of waves. Even the air contains molecules, which have wave-like characteristics. Balsa wood can be split into twenty-four transverse and longitudinal wave. Each of these waves has a definite frequency, which determines the characteristics of the object and can be detected using an instrument known as an optometer.
How Light Emits Waves
Some objects also emit light and sound waves. For example, light rays emitted by a flashlight or spotlight can be recorded by a camera. This enables us to recognize people in bright light by their appearance. Similarly, microwaves and infrared waves are emitted from stars and space gases. Telescopes detect these waves.
We cannot see through objects, but we can hear them if they contain sound waves. The human voice is the result of the compression of sound waves while traveling through a medium. Thus, we can distinguish sound waves by their frequency. The human voice has a frequency close to the frequency of the electromagnetic waves emitted by the sun or the moon. Similarly, the sound created by birds and waterfalls has a frequency close to the frequency of the light waves.
Light waves have certain specific wavelengths and certain frequencies. For example, all visible light waves have a wavelength of about 7 centimeters. While the eyes cannot detect anything below this wavelength, we can see objects clearly at a very close distance. This is the reason why we can distinguish the outline of an object by staring at it with our hands-on.
However, when human eyes move away from a source of light or sound, the human eye’s capability of seeing diminishes. It becomes difficult to detect details and colors. Thus, it is impossible to see an object at a distance of more than a few feet. In such situations, our brain has to take some help. It compares the movement of electromagnetic waves with the speed of their moving vibrations.
Speed Of Sound Waves
The speed of the particles in a fluid increases as a result of friction. This change is also propagated throughout the volume of the fluid. The change in the speed of sound waves is also related to the change in the amplitude of sound wave. Thus, sound waves have different amplitude depending upon the frequency of the transmission. If we use a microphone to listen to the sound, the changes in the frequency level are recorded by the microphone.
The micron size is selected in order to give maximum performance. Similarly, the frequency of transmission has a corresponding effect on the sound wave amplitude. The larger the bandwidth of transmission, the smaller the amplifying factor, i.e., the power required for the same amplitude. Thus, we hear sounds with larger bandwidth but with the same amount of loudness at the same level of amplification. Similarly, the smaller the bandwidth, the louder it is. It is also interesting to note that the wavelength of light and sound waves vary inversely with the diameter of the medium, i.e., the wavelength of light increases as the size of the medium increases.
Light and sound waves behave differently because different processes produce them. They can also be transmitted via different sources. However, once the source of light or sound has been selected, one can determine the frequency level that best expresses the electrical charge of the sample. Thus, one can use this technique to evaluate and communicate information to various parts of a device or system.
Also Read ” Forms of Energy“
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