Amplitude in Physics

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As we here sound every day and sometimes we enjoy it as well while sometimes we get irritated. Here, we will learn about a few terms which are related to sound. The term amplitude in physics is said to be the maximum displacement or distance that is moved by a point on a body which is vibrating or wave measured from its equilibrium position. It is more or less said to be equal to one-half the length of the vibration path. The amplitude of a pendulum is thus one-half the distance that the bob traverses in moving from one side to the other while oscillating. Waves are generated by the source which is vibrating. 

Amplitude Definition Physics

For a wave that is transverse in nature, such as the wave on a string which is plucked there the amplitude is measured by the maximum displacement of any point which is present on the string from its position when the string is at rest. For a wave which is longitudinal in nature such as the sound wave there the amplitude is measured by the maximum displacement which is done by the particle from its position of equilibrium. We need to note here that when the amplitude of a wave steadily decreases, this is because its energy is being lost and it is said to be damped.


A sound is a form of energy that is produced by vibrating bodies. Sound generally requires a medium for its propagation. Hence we can say that sound cannot propagate in a vacuum as there will be no material through which sound waves could get transferred. The back and forth motion of an object due to which sound is produced is called a sound vibration. It is also sometimes known as motion that is oscillatory motion. The rhythmic motion which is back and forth movement is referred to as the process of oscillation.


The amplitude of a variable which is periodic is a measure that is of its change in a single period; we can say that such as time or period which is spatial . There are various definitions which can be given for term amplitude. These are all functions of the magnitude of the differences which is between the variable's extreme values. In older texts, we could see that the phase of a periodic function is sometimes known as the amplitude.

In an audio system of measurements, such as the telecommunications and others where the measurement of a signal swing moves above and below reference value but is not sinusoidal. The amplitude which is the peak amplitude is often used there. If the reference is taken as zero then we can say that this is the maximum absolute value of the signal. so if the reference is a mean value that we can say is the DC component the peak amplitude that is said to be the maximum absolute value of the difference that is from that reference.

Semi-amplitude generally means half of the peak-to-peak amplitude. Some of the scientists use peak amplitude or amplitude to mean semi-amplitude.

In general, we can say that the use of the amplitude or the peak amplitude is simple and unambiguous only for symmetric periodic waves. For example, a sine wave that is a square wave or we can say that a triangle wave. For a wave which is asymmetric, that is the periodic pulses in one direction as we see the peak amplitude becomes ambiguous. This usually occurs because the value is different, that is depending on whether the maximum positive signal is measured relative to the mean and the maximum negative signal is measured relative to the mean. or at times we can say that the maximum positive signal is measured relative to the maximum negative signal that is the peak-to-peak amplitude and then divided by two the semi-amplitude. In the field of electrical engineering the usual solution that is given for this ambiguity is to measure the amplitude from a defined reference potential such as ground or 0 V. Strictly speaking, we can say that this is no longer amplitude since there is the possibility that a constant that is DC component is included in the measurement.

Define Amplitude in Physics

The amplitude which is the peak-to-peak amplitude that is the abbreviated p–p is the change between peak that is the highest amplitude value. The lowest amplitude value can be negative as well. Sp with appropriate circuitry we can say that the peak-to-peak amplitudes of electric oscillations can be measured by meters or by viewing the waveform on an oscilloscope. The p-p or the peak-to-peak amplitude is a straightforward measurement on an oscilloscope. That way we can say the peaks of the waveform are easily identified and measured against the graticule. This generally remains as a common way of specifying amplitude but sometimes we can say that the other measures of amplitude are more appropriate.

For alternating current electric power generally, the universal practise is to specify RMS values of a sinusoidal waveform. 

FAQ (Frequently Asked Questions)

Q1. Explain Amplitude and Frequency.

Ans: For the term waves these variables have the same basic meaning we can say that. The term that is amplitude which is the distance between the resting position and the maximum displacement of the wave. The term that is frequency is said to the number of waves passing by a specific point per second. And the term period is defined as the time it takes for one wave cycle to complete.

Q2. Explain What is Amplitude in Physics Class 8.

Ans: The maximum displacement that is of an object which is vibrating from its Central position is known as the amplitude of vibration. The amplitude actually tells us how far the object which is vibrating is displaced from its central position.

Q3. What is the Amplitude of the Signal?

Ans: The term which is amplitude is said to be the distance from the equilibrium position of the medium to compression or we can say a rarefaction. The value of the peak of sinusoidal AC signals is referred to as starting from zero line amplitude. The term which is amplitude usually refers to the scalar or we can say the vector field size.

Q4. How is Amplitude Expressed in Units?

Ans: The term amplitude is generally measured in metres. That is the greater the amplitude of a wave then the more energy it is carrying into it. We can normally use a time which is of one second so this gives a frequency of the unit hertz since one hertz is said to be equal to one wave per second.