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Travelling Waves - JEE Important Topic

Last updated date: 05th Dec 2023
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Where are Waves?

According to Webster's dictionary, a wave is a disturbance or variation that causes energy to be transferred gradually from one point to another in a medium; it can be an elastic deformation or a change in pressure, electric or magnetic intensity, electric potential, or temperature.

The definition's key point is that a wave is a disturbance or fluctuation that propagates through a medium.  When a wave passes on a medium in which the wave travels may experience some oscillation but the particles present in the medium will not move with the wave. The disturbance could be in the form of a sine wave with indefinite length or a pulse with finite width.

For example, the sound that we hear, the light that affects our eyes to process accordingly, and the radiation of electromagnetic radiation on our phones all travel in the form of waves. One of the prominent examples that we can get about the propagation of the waves is throwing a stone into the water in which waves are formed. 

Types of Waves and Their Importance

There are some types of waves that have distinctive characteristics according to their dominance. The particular characteristics of the waves help us distinguish their features and importance. The aspect of the particle motion that is relative to the directional exposure of wave propagation is one of the significant ways in which the distinguishing features of the waves are determined. Let us focus on the type of waves and how they influence energy. 

  • Pulse Waves

A pulse wave is determined to be a wave that consists of only individual disturbance or one crest that will move through the medium of transmission. Pulse waves are considered to be very crucial and give a handful of measures to the world of physics. 

The speed of wave is interrelated to the wavelength and the frequency of the wave, which derives the equation of speed of wave formula that is Speed = Wavelength x Frequency. This equation should be followed up when the wavelength and the frequency are known to you. 

  • Continuous Waves

Continuous waves, or they can be termed the continuous waveform, are known to be the electromagnetic wave of static amplitude and frequency and in the mathematical representation or infinite timeframe. Continuous wave is also a name that denoted the early process of radio transmission, in which the switching on and off of the carrier wave is implemented. Information is known to be carried out as wave travel during the on and off processing of the signal. This type of wave is also known as the periodic wave. 

  • Transverse Wave Definition

Transverse waves describe that the particle’s motion is directly perpendicular to the propagation direction of the wave. It is defined as the motion in which oscillation of the wave occurs at all points along with the access at right angles to the direction of the advance of the waves. The speed of the wave continuously fluctuates in this type. Some of the prominent examples of transverse waves are the rippling surface of the water and electromagnetic waves such as light and radio. 

  • Longitudinal Waves

Longitudinal waves denote that the waves to which the particle’s motion is adhering will remain in the same direction as the propagation of the travelling wave. 

All the types of waves are different and share their distinctive characteristics and approaches when they collide with physical use. There is one significant property that shares the common attribute with all the types, and that is the transportation of the energy within them. An object which is in the simple harmonic motion consists of the energy of, 


Following the equation, we can get that the wave’s energy has the direct proportionality to the square of the amplitude, which implies,

$E\propto {{A}^{2}}$

This particular relationship between the amplitude and the energy is significant in knowing the destruction caused by the shock waves from a massive earthquake. This implies that when the waves start spreading, their power becomes weaker as the distribution of the energy has been done over a larger area. 

Travelling Wave Theory

Let us discuss what is travelling wave?

Travelling wave theory focuses on the ideology that if there is any negligence in the transmission procedure line, it will give rise to travelling waves along the transmission line. 

These travelling waves are considered to be the charge and discharge of the capacitance that is the line inductance from the transmission line. The individuality of the waves consists of frequencies, from a small kilohertz to huge megahertz, which have a propagation speed among the speed of light.

The equation of travelling wave on a stretched string is given as:

\[y=A{{e}^{-{{\left( \frac{x}{a}+\frac{t}{T} \right)}^{2}}}}\]

Constructive and Destructive Interference

An ideology in which two waves impose each other to be the result of greater, lower, or for the same significant amplitude is considered to be the interference. The formation of the constructive and the destructive interference happens because of the interaction between the waves that are termed to be correlated with one another due to the same frequency or because of their existence from the same source. The effects of the interference can be valued in all types of waves like light waves and gravity waves. 

Valuing the concept of superimposition of the waves, when one or more propagating waves of a similar type are resulting in incidents on the same spot, the resultant amplitude remains equal to the sum of the vector of the amplitude along with the individual waves. When the crest of a wave encounters the crest of another wave of a similar frequency, the resultant amplitude will be the sum of the individual amplitudes. This kind of interference is termed to be constructive interference. 


Here we have covered the basic characteristics and the types of travelling waves and their potential in day-to-day life. The travelling wave theory describes the natural phenomenon of the waves, and along with that, we have learned about the features of constructive and destructive interference. 

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FAQs on Travelling Waves - JEE Important Topic

1. How do you determine the types of travelling waves?

We can mainly consider the types according to their three basic principles. They are classified as mechanical waves, matter waves, and electromagnetic waves. The basic implementation of the mechanical waves is ruled by Newton’s laws and desires a medium to work. A medium is considered to be the substance in which the propagation of mechanical waves occurs. The medium also gives rise to the elastic restoring force in the deforming process.

2. How do you differentiate between travelling and a standing wave?

Travelling waves are considered to be the carrier of energy from one space area to the other. On the other hand, standing waves have the consistency of not transporting energy. Points that remain in the standing wave will have their oscillation phase, where the travelling waves only focus on the wavelength apart from oscillating in phase. The rest upon the wavelength oscillates with the original point being out of phase. A standing wave works by getting attached to the two fixed spots or points, whereas the travelling wave has the characteristics to move freely.