Explain the term amplitude of a wave. Draw the diagram of a wave and mark its amplitude on it.


A wave is a continuous disturbance that propagates from one point to another point. There are different types of waves that travel through mediums. Mainly there are two types of waves.

Mechanical waves: A wave that requires a medium to propagate. For example, sound signals travel in the medium, and water waves propagate on water

Electromagnetic waves: These waves propagate in a vacuum. For example, light waves propagate in space.

Usually, waves propagate in the form of crust and trough. and each wave has some characteristics like amplitude, velocity, frequency, and so forth. When describing waves, the amplitude is an energy measurement. In the case of electromagnetic radiation, a wave is a pulse of energy that moves across a medium or through empty space.

Define the Amplitude of a wave

Amplitude is a measurement of the energy transferred by a wave; the more energy put into a wave, the larger the amplitude or the separation between the axis from the end of a peak or the end of a valley is called an amplitude (A) of a wave.

The amplitude is expressed in meters (m). A wave's amplitude determines how much energy it carries. It estimates how much a wave rises and falls. if a wave has a large amplitude, they have high energy, whereas low amplitude waves have low energy. An equation for a sinusoidal wave can be written as

$$\mathrm{x=A\:sin(\omega t+\Phi)}$$

Where: x= displacement of wave

A= amplitude of wavex

ω= angular frequency

t= time

ϕ= phase angle

The energy required to generate motion in a particle is expressed in the degree of displacement which is estimated as the amplitude of the wave.


Sound is an energy that causes vibration in an object. These vibrations transfer energy from one place to another through a medium such as solid, liquid, or gas. Since sound is a kind of longitudinal wave so it propagates in the form of compression and rarefaction. When a body produces a sound, then the vibration of the body transfers its energy to air molecules, causing a chain reaction that grows through the air until it comes to our eardrums. Signals are delivered to our brain when our ears pick up that sound, allowing us to understand what we're hearing.

The sound which is audible by human beings lies in the range of 20Hz to 20KHz, and sound above and below this range is known as ultrasound and Infrasound. Ultrasounds waves: These waves are mostly used in the medical field in the diagnosis of various diseases like electrocardiography, sonography, lithotripsy, and so forth.

Infrasonic waves: It is a low-frequency wave and most commonly observed in natural phenomena like volcanic eruptions, earthquakes, and so on

Define Amplitude in Physics?

Amplitude is determined from the maximum separation or distance travelled by a point on a vibrating body or wave from its stationary points. All wave carries some amplitude.

In physics, the Amplitude of waves can be modulated by amplitude modulation. In this process, a low amplitude wave is transmitted data from source to destination with help of a carrier wave. This amplitude modulation finds application in the transmission of signals, radio broadcasting, and so forth.

Characteristics of Sound


A sound's pitch is the sense of frequency. A high-frequency sound wave refers to the high-pitched sound, while a low-frequency sound wave correlates to a low-pitched sound. It is expressed in Hertz (Hz).


The size of the wave determines the loudness phenomena of sound. If the size of the sound wave is large means the signal is loud. It is expressed in decibel (dB).


It is the maximum relegation of particles disturbed by a sound wave as it crosses the medium. It is expressed in meter (m).


Sound is a longitudinal wave that travels through a medium and experiences compressions and rarefactions. It's the space between the core of two consecutive rarefactions or compressions or the length of compression plus the adjacent rarefaction. It is expressed in angstrom (Å) which is equal to 10-10 metre.



The number of sound waves generated per second is referred to as frequency. If a wave has a low frequency, then it has fewer waves than one with a high frequency. The frequency of sound is estimated in hertz (Hz)


Time Period

The time it takes for a medium particle to complete one vibration is referred to as the wave's time period. It is expressed in seconds (sec).



The velocity of a sound wave is the rate at which the disturbance is transmitted from one particle to the next. It is expressed in (ms-1).



In our day-to-day life, we deal with different kinds of waves like the sun waves, water waves and sound waves. Waves are just a transfer of energy in the form of disturbance.

Sound waves are generated by a vibrating body that transfers their energy to molecules present in the atmosphere. Hence the sound waves are propagated. Sounds are of many types like pleasant sound, noise, music, etc. the characteristic of sounds play an important role in the generation of music or any other type of sound.


Q1. Write differences between pitch and loudness?


A sound's pitch is the sense of a frequency. A high-frequency sound wave refers to the high pitch sound, while a low frequency sound wave correlates to a low pitch sound.The amplitude of the sound wave determines the loudness phenomena of sound. The sound is said to be loud if the amplitude of the sound wave is large.
The SI unit of pitch is Hertz(Hz).The SI unit of loudness is the decibel (dB).
Pitch is proportional to the frequency.Loudness is proportional to the square of the amplitude.

Table-1: Difference between Pitch and Loudness

Q2. Distinguish between pitch and frequency?

Ans. The frequency refers to how often an occurrence occurs. For the sake of simplicity, we'll refer to frequency as the number of occurrences per second. Pitch is a term that is deeply intertwined with frequency. The frequency with which a sound oscillates is proportional to its pitch. The property of frequency is explored in all types of waves, including electromagnetic and mechanical waves. Pitch is a quality that is exclusively considered in relation to sound waves. Pitch is a difficult concept to define.

Q3. What is the hearing range of the human ear?

Ans. Humans can notice sound in the 20 Hz to 20 kHz frequency range. Interestingly (Human new born can hear frequencies slightly higher than 20 kHz, but as they grow older, they lose some high-frequency sensitivity.)

Q4. Write the equation which shows the correlation between wavelength, frequency, and velocity?

Ans. The relation between wavelength, frequency and velocity can be given by the following equation.


As we can see in the formula; wavelength and velocity are directly proportional to each other whereas wavelength and frequency are inversely proportional to each other. Velocity and frequency are directly proportional to each other.

Q5. Write the wavelength equation in three different formats.

Ans. To find wavelength


To find frequency


To find velocity


Updated on: 28-Apr-2023


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