Difference Between Wavelength and Amplitude

Wavelength vs Amplitude

Wavelength and amplitude are two properties of waves and vibrations. Wavelength is a property of a wave but the amplitude is a property of a wave as well as an oscillation. The concepts of wavelength and amplitude are widely used in fields such as waves and vibrations, communication, light and other electromagnetic radiation and various other fields. In this article, we are going to discuss what wavelength and amplitude are, their definitions, the similarities between these two, their applications and finally the difference between wavelength and amplitude.


Amplitude is a very important property of a periodic motion. To understand the concept of amplitude the properties of harmonic motions must be understood. A simple harmonic motion is a motion such that the relationship between the displacement and the velocity takes the form of a = -ω2x where “a” is the acceleration and “x” is the displacement. The acceleration and the displacement are antiparallel. This means the net force on the object is also on the direction of the acceleration. This relationship describes a motion where the object is oscillating about a central point. It can be seen that when the displacement is zero the net force on the object is also zero. This is the equilibrium point of the oscillation. The maximum displacement of the object from the equilibrium point is known as the amplitude of the oscillation. The amplitude of a simple harmonic oscillation strictly depends on the total mechanical energy of the system. For a simple spring – mass system, if the total internal energy is E amplitude is equal to 2E/k, where k is the spring constant of the spring. At the amplitude, the instantaneous velocity is zero thereby the kinetic energy is also zero. Total energy of the system is in the form of potential energy. At the equilibrium point, the potential energy becomes zero.


Wavelength is a concept discussed under waves. The wavelength of a wave is the length where the shape of the wave starts to repeat itself. This can be also defined using the wave equation. For a time dependent wave equation ψ(x,t), in a given time if the ψ(x,t) is equal for two x values and there are no points between the two points having the same ψ value, the difference of x values are known as the wavelength of the wave. The relationship between the wavelength, frequency and the velocity of the wave is given by v = f λ where f is the frequency of the wave and λ is the wavelength. For a given wave, since the wave velocity is constant the wavelength becomes inversely proportional to the frequency.


What is the difference between Wavelength and Amplitude?

• Wavelength is a property that is defined only for waves but the amplitude is defined to vibrations or oscillations.

• Wavelength is a property that is connected with the velocity and frequency of the wave, whereas the amplitude is a property that is dependent on total energy of the oscillation.