An individual is completely dependent on a wide range of waves for wireless communications. When you call your friend then the entire communication on the phone happens through the transmission of waves. The communication from the sender to the receiver appears in the form of a waveform. Your phone converts the received voice signal into an electrical signal. Later, these electric signal travels either wirelessly or via copper wires to the receiver through an antennae. In this way, waves help in communication between people.
Types of Waves:
Waves occur in various forms. There are three types of Waves
Mechanical Waves
Transverse waves
Longitudinal waves
Electromagnetic waves
Matter Waves
1) Mechanical waves
The mechanical waves are seen as a propagation of a specific disturbance that travels in a material medium. This type of wave is a result of the oscillation of matter. In this case, the transfer of energy happens through a medium.
The oscillating material performs motion at a stationary point. There is little translational motion involved in this type of propagation. The distance covered by the propagation of a wave is determined by the transmission medium.
This wave is the outcome of the continuous periodic movement of the particles. In this type of wave, the entire disturbance that comprises of momentum and energy is passed from one wave-particle to its immediate next particle in the medium. Mechanical waves do not possess the ability to pass through the vacuum. There is no mass transfer possible during the movement of wave particles.
Some of the examples of a mechanical wave are the “vibration of a string”, tsunami waves, earthquake waves, ultrasounds, waves in slink, oscillations in spring etc.
Mechanical waves are measured by dividing displacement by the wavelength. When the dimensionless factor is below one, it generates harmonic effects. When this factor increases from one, then it becomes the reason for turbulence. It is seen in the form of waves breaking on the beach.
There are two types of Mechanical waves, as Transverse waves and Longitudinal waves
a) Transverse Waves
In this type of wave, the medium vibrates to and fro at right angles to the direction of propagation of wave/energy. In other words, when the energy particles and the wave particles form a perpendicular angle to each other, then it is called a transverse wave. One of the best examples of transverse waves is radio waves, microwaves, ocean waves, wiggling string and polarized waves.
b) Longitudinal Wave:
This is another important variation of a wave. Here, the wave particles vibrate to and fro in the direction of the propagation of wave/ energy. There is a zero-degree angle formed between the wave particles and the energy particles. It can also be put as the displacement of the medium occurs in the direction of the movement of the wave. Some of the examples of this type of longitudinal wave are sound waves, and pressure wave.
2) Electromagnetic Waves
In electromagnetic waves, there is no need for the presence of any medium for the propagation of the wave. In other words, electromagnetic waves travel from one place to another in a vacuum and at the same speed. As in these waves, periodic changes take place in the magnetic fields; they are called as electromagnetic waves.
Electromagnetic waves are formed by the combination of magnetic and electric fields. The light and the colour that you see are due to the presence of electromagnetic waves. Some of the important examples of electromagnetic waves are: Microwaves, Lightwaves, thermal radiation, X-rays, Radio waves and Ultraviolet waves
Properties of Electromagnetic Waves:
There are some important attributes of electromagnetic waves as mentioned below:
These waves travel with the speed of light.
They can be polarized.
They show a transverse nature.
They carry momentum
3) Matter Waves
These waves are also referred to as De Broglie waves. According to Louis de Broglie’s theory, a beam that comprises of electrons can get deflected like any other ray of water wave or electromagnetic radiation.
These types of waves show properties similar to the properties of a matter, such as atoms, etc. There are various equations represented as De Broglie's equation that signifies the “dual” nature of matter. The frequency of matter waves is directly dependent on the kinetic energy.
Properties of Waves
A wave is characterized by different properties of it. These properties are amplitude, frequency, wavelength, velocity and period. To get more clarity on these elements, let us understand each of them one by one.
Amplitude
The amplitude of a wave is measured in meters. It denotes the energy contained in the wave. The wave that has more amplitude is more powerful and energetic. The amplitude of a wave is the maximum displacement or the total distance travelled by a wave in the medium.
Wavelength
Wavelength is calculated as the distance between two successive troughs or crests of the wave. It is measured in meters. Wavelength of a wave is denoted by lambda and it is equal to the velocity of a wave (in meters/sec) divided by the wave frequency (in Hertz).
Time Period
Time Period is the total time that a wave takes to complete a single cycle. It is measured in seconds. It is represented by the alphabet ‘T’. The inverse of the time period is the frequency of a wave.
Velocity
The velocity of any wave is the speed at which a wave travels in one medium. It is measured in meters/seconds. Velocity is calculated as the product of wave frequency and the wavelength, or division of wavelength and the period.
Wave Speed Formula
Having understood the different types of waves, let us now understand Wave Speed Formula. Wave speed is viewed as the distance that any wave travels at a specified amount of time. It implies the number of meters that a wave travels in every second.
Wave speed is also related to wave frequency and wavelength. It can be understood by the following equation:
Speed = Frequency x Wavelength
When you know the values of the frequency and the wavelength, you can easily calculate wave speed with this formula.
FAQs on Wave
1. What is a wave in the context of Physics?
In physics, a wave is defined as a disturbance that travels through a medium or space, transferring energy from one point to another without causing any permanent displacement of the medium itself. The particles of the medium oscillate about their fixed equilibrium positions as the wave passes through.
2. What are the main types of waves studied in Class 11?
Waves are broadly categorised into two main types based on the medium they require for propagation:
- Mechanical Waves: These waves, such as sound waves or ripples on water, require a material medium (solid, liquid, or gas) to travel. They are further classified as transverse or longitudinal.
- Electromagnetic Waves: These waves, such as light or radio waves, do not require a medium and can travel through a vacuum. They consist of oscillating electric and magnetic fields.
3. What is the fundamental difference between a transverse wave and a longitudinal wave?
The fundamental difference lies in the direction of particle oscillation relative to the direction of wave propagation. In a transverse wave, particles of the medium oscillate perpendicular to the direction of energy transfer (e.g., light waves, waves on a string). In a longitudinal wave, particles oscillate parallel to the direction of energy transfer, creating compressions and rarefactions (e.g., sound waves).
4. What are some real-world examples of wave motion?
Wave motion is observed everywhere in the natural world and technology. Some common examples include:
- Ripples spreading across the surface of a pond.
- Sound travelling from a speaker to our ears.
- Light waves travelling from the sun to the Earth.
- Seismic waves (P-waves and S-waves) generated during an earthquake.
- Microwaves used for cooking and communication.
5. What is the Principle of Superposition of Waves?
The Principle of Superposition states that when two or more waves of the same type overlap at a point in a medium, the resultant displacement at that point is the vector sum of the individual displacements that each wave would produce on its own. This principle is fundamental to understanding phenomena like interference, beats, and standing waves.
6. Why does sound require a medium to travel, but light does not?
This is because they are fundamentally different types of waves. Sound is a mechanical wave, meaning it is a vibration of particles. It needs to pass this vibration from one particle to the next, so it requires a medium (like air, water, or a solid) to propagate. In contrast, light is an electromagnetic wave, which is a disturbance in electric and magnetic fields. These fields can exist and propagate in a vacuum, so light does not need a material medium to travel.
7. What are standing waves and how are they formed?
A standing wave, also known as a stationary wave, is a wave that oscillates in time but whose peak amplitude profile does not move in space. It is formed by the superposition (or interference) of two identical waves travelling in opposite directions. This typically occurs when a wave reflects off a boundary and interferes with the original incident wave, creating points of no displacement called nodes and points of maximum displacement called antinodes.
8. How does the superposition principle explain phenomena like interference and beats?
The superposition principle is the direct cause of interference and beats.
- Interference: When two waves with the same frequency and a constant phase difference superpose, they create a stable pattern of high and low intensity. Where they are in phase, they cause constructive interference (larger amplitude). Where they are out of phase, they cause destructive interference (smaller or zero amplitude).
- Beats: When two sound waves with slightly different frequencies superpose, the resulting sound has a periodically varying amplitude, which we perceive as a 'beating' or 'throbbing' sound. The beat frequency is equal to the difference between the frequencies of the two original waves.
9. What is the Doppler effect and where can we observe it?
The Doppler effect is the apparent change in the frequency (and wavelength) of a wave in relation to an observer who is moving relative to the wave source. A common example is the change in pitch of an ambulance siren: the pitch sounds higher as the ambulance approaches you (waves are compressed) and lower as it moves away (waves are stretched out).
10. What is the physical importance of harmonics in musical instruments?
In musical instruments like guitars or flutes, harmonics (or overtones) are crucial for determining the timbre or quality of the sound. While the fundamental frequency determines the note's pitch (e.g., Middle C), the presence and relative intensity of various harmonics are what make a flute playing Middle C sound distinctly different from a violin playing the exact same note. Harmonics give a sound its rich and unique character.
