For any sound wave unit of aptitude is
Answers
The intensity of a sound wave has units of Watts/meter. ... The ability of an observer to hear a sound wave depends solely upon the intensity of the sound wave.
Answer:
Amplitude Of A Wave
Sound Waves
Frequency/ Pitch of the Sound Waves
Frequency in a sound wave refers to the rate of the vibration of the sound travelling through the air. This parameter decides whether a sound is perceived as high pitched or low pitched. In sound, the frequency is also known as Pitch. The frequency of the vibrating source of sound is calculated in cycles per second.
The SI Unit for Frequency being hertz and its definition being ‘1/T’ where T refers to the time period of the wave. The time period is the time required for the wave to complete one cycle. Wavelength and frequency of a sound wave are related mathematically as:
The velocity of Sound = Frequency * Wavelength
The below graphs can be used for understanding more about sound. The first graph represents a sound wave from a drum while the second graph represents the sound wave from a whistle. You probably already know the difference in the sounds but have a look at the difference in their frequencies.
Sound Waves
Two graphs showing the difference between sound waves with high and low frequencies and their corresponding pitches
Timbre
Imagine a bell and a piano in an orchestra. The same musical notes can be obtained by both the instruments but their sounds are very different. The piano produces a distinct note whereas the bell struck to the same pitch and amplitude produces a sound that continues to ring after it has been struck. This difference in the sound is referred to as the Timbre. Timbre is actually defined as; if two different sounds have the same frequency and amplitude, then by definition they have different timbres.
What are Sound Waves?
A sound is a form of energy, just like electricity, heat or light. When you strike a bell, it makes a loud ringing noise. Now instead of just listening to the bell, put your finger on the bell after you have struck it. Can you feel it shaking? This movement or shaking, i.e. the to and fro motion of the body is termed as Vibration. The sound is a vibration that moves as an audible form of energy through a medium. The sound moves through a medium by alternately contracting and expanding parts of the medium it is travelling through. The movement of molecules of a medium is essential for the propagation of sound waves. Hence sound waves cannot travel through the emptiness of vacuum.
Characteristics of Sound Waves
Sound cannot travel through a vacuum. This is very much in contrast with the property of light. Another difference which is above the scope of the syllabus is the fact that sound waves are generally longitudinal waves and light waves are transverse waves. But they’re not very different either. Let’s take a look at the characteristics of sound when propagating through air.
Reflection of Sound Waves:
This property of sound is responsible for the phenomenon of the Echo. Also, the rolling of thunder is largely due to the repeated reflections from the clouds and land surfaces. The reflection of sound follows the same principle as light waves. The angle of incidence is equal to the angle of reflection. For an appreciable reflection, the reflecting surface should have a large surface area, like a cloud. This principle of reflection is used in a technology known as SONAR (Sound Navigation and Ranging) where the sound waves are used, usually underwater, to navigate and communicate. The sound waves that reflect from objects are used to detect objects on or under the surface of the water.
sound waves : reflection
Refraction of Sound Waves:
Refraction in light occurs when the density of the medium in which light is travelling changes. Similarly, Refraction in Sound occurs when the density of the atmosphere it is travelling through changes. The density of a gas decreases with the rise in temperature, inversely proportional. In fact, it is so similar to light waves that it even undergoes Total Internal Reflection.
refraction of sound waves
Diffraction of Sound Waves:
Think about this for a minute. If you shut the door and shout for your friend outside your room, he can still hear you. Sound waves have the ability to bend around obstacles. If there is a small hole in the door, the small opening itself would act as a localized source of the sound. The diffraction of sound waves is an important part of our experience of the world around us. The lightning strikes close to your sound like a sharp crack and yet the distant strikes sound of deep rumbling thunder. This is because the deeper tones of sound waves can bend across obstacles better than the sharp sounds so you hear only the deep rumbling. Light waves too undergo diffraction but of a significantly lesser magnitude.
sound wave : defraction
We started off saying sound and light waves are not alike at all. But by the end, the sound seemed more like light waves.