What is Amplitude?
You may have observed the waves of sound traveling in air, and waves of ripples in water. If you touch the tip of your pencil or pen to the still water of a container, you will notice that the water surface gets disturbed and produces ripples or waves.
Electromagnetic waves like light waves, microwaves, radio waves and x-ray do not require any medium for their propagation. These waves cannot be seen or heard, but these waves exist in nature and are used in many ways, in day-to-day life.
Every type of wave has some amplitude. Amplitude is the maximum displacement of the wave about its mean position. This maximum displacement or amplitude of a wave is measured in terms of the mean position or equilibrium position of the wave.
The diagram below represents the amplitude and wavelength of a wave. Wavelength is the distance between two consecutive crests or two consecutive troughs of a wave. The uppermost or highest position of a wave is called a crest, and the lowermost position of a wave is called a trough. Time period is defined as the time required completing one full cycle of the wave.
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What is Amplitude Formula?
The formula to calculate amplitude is mentioned below:
x = A sin(ωt+ϕ)
Where,
x = displacement of wave, in metres.
A = amplitude of wave, in metres
ω = angular frequency of wave, in radians.
t = time, in seconds.
ϕ = Initial phase, in radians.
Amplitude and Frequency
Frequency is defined as the number of wave cycles which passes a point per second. It is the number of oscillations that occurs in a wave per second. Frequency is inversely proportional to wavelength. So, the higher the frequency, lower will be the wavelength and vice versa.
Wavelength and frequency are related to each other, but amplitude and frequency are completely independent features of a wave. Both amplitude and frequency can be changed, but a change in one parameter doesn't affect the other. A change in frequency doesn't change the amplitude of the wave, and a change in amplitude doesn't change the frequency of the wave.
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The amplitude of a wave cannot be determined by knowing the value of frequency of the wave. Also, the frequency of a wave cannot be determined by knowing the amplitude of the wave.
Amplitude and Frequency of a Ferris Wheel
The oscillatory motion (height of a passenger in this case) in a Ferris wheel, relative to the center of Ferris wheel, given by the function:
F(t) = Asin(ωt+ϕ) + B,
The time period of this cycle is: \[\frac{2\Pi }{\omega }\]
The phase shift of this cycle is given by:
Where,
A = amplitude
B = vertical shift
Amplitude of Sound
Sound is a form of energy by which we can hear. If you strike a bell, it produces sound. You can feel the vibration of the bell, if you touch it. You can notice that the bell is shaking. This to and fro motion of the bell is called vibration.
The amplitude of a wave, (like that of a sound wave) is the measure of the displacement from the mean position. The amplitude of a sound wave is defined as the maximum displacement of the wave from the equilibrium position.
Mathematically, it is the distance between a crest and the equilibrium position of a sound wave.
The sine wave is given by the equation:
y = A sin ω t
Where,
A = amplitude of the wave,
ω = angular frequency of the wave,
t = time taken
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The amplitude of the wave will change depending upon its oscillation. The loudness of a sound wave varies directly in relation to its amplitude. Higher is the amplitude, higher will be the sound. If the amplitude is low, the sound produced will also be less.
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Time Period in Sound
An event is said to be periodic if it occurs repeatedly. The time taken by a sound wave to complete one cycle is called its time period. The time period is inversely proportional to frequency, and is given by:
Time Period = 1/Frequency
Frequency in Sound
The number of oscillations made by the sound wave per second is called its frequency. The SI unit of frequency is hertz, and is denoted by Hz. Frequency describes how many times a particle vibrates when the wave travels through a medium.
Frequency = 1/Period
FAQs on Amplitude Frequency Period Sound
1. What Is The Difference Between Amplitude And Frequency?
The major differences between amplitude and frequency of sound are mentioned below:
Amplitude is the maximum displacement of the particles of a sound wave. Frequency is the number of vibrations made by a sound wave per second.
Amplitude describes the size of sound waves. Frequency describes the number of waves per second.
Amplitude is measured in metre and Frequency is measured in hHertz.
Amplitude measures the loudness of sound. Frequency measures the shrillness of sound.
Higher the amplitude louder will be the sound. Higher the frequency, shriller will be the sound.
Humans are only able to hear frequencies between 20Hz and 20,000 Hz whereas amplitude doesn't have such a fixed amount for human hearing.
2. How Do Frequency, Amplitude, And Wavelengths Affect Sound?
Effect of wavelength on sound :
Short wavelength gives rise to high frequency with higher pitch, and faster cycles.
Long wavelength gives rise to low frequency with lower pitch and slower cycles.
Wavelength doesn't affect the speed at which the wave travels but the change in wavelength occurs when sound travels from one medium to another.
Effect of amplitude on sound :
Amplitude determines the volume of a sound wave. It is not related to frequency. Thus, it is possible to have a loud sound wave of low frequency, or a quiet sound wave of high frequency.
Amplitude also determines the size of the vibration. Therefore, it also affects the bass and depth of the sound produced.
Effect of frequency on sound :
Frequency also decides the way something sounds. Therefore, frequency is responsible for affecting the pitch of the sound. The more the frequency of sound waves, higher will be it's pitch and vice versa.
3. What Are The Characteristics of Sound waves?
Unlike light waves, sound waves cannot travel through vacuum.
Sound waves are longitudinal waves, whereas light waves are transverse waves.
Characteristics of sound wave :
Low frequency sounds produce lesser sound waves per second than high frequency sounds.
The wavelength of a soundwave is the distance that the wave will travel (before repeating itself).
The velocity of the sound wave explains that the speed at which sound is moving is a particular direction
The time taken to complete a full wave cycle is called the time period of that sound wave.
4. Explain the Propagation of Sound Waves.
The kinetic energy created during the vibration of an object is transmitted in the medium by the molecules. This process is known as the Propagation of Sound Waves. These vibrations come in air contact and pass their kinetic energy further (to the nearby molecules). These molecules get energized due to the passage of kinetic energy. They energize other molecules and the process is repeated. During this transmission of the energy from one molecule to the next, some amount of kinetic energy is lost during the transmission. When the kinetic energy produced by the vibration is used up completely, the transmission stops. This means, the sound wave is propagated completely.
5. Differentiate between Sound waves and electromagnetic waves.
Sound waves are produced by mechanical vibrations but electromagnetic waves are produced by charged particle's acceleration or deceleration.
Sound waves require a medium to travel but electromagnetic waves do not require a medium to travel.
Sound waves are longitudinal waves whereas electromagnetic waves are transverse waves
Sound waves are created during playing of musical instrumentals, scratching of objects and striking etc. Electromagnetic waves can be produced by a current carrying wire. Blackbody radiations are also a source of electromagnetic waves.