Properties of Waves

Waves carry energy via propagating through a medium. The speed and properties of the wave depend on the medium, and sound waves travel faster in less dense mediums. Temperature is directly proportional to wave motion. There are two waves – longitudinal and transverse, which are further explained in the article. Waves transfer the energy through a medium without the actual transfer of matter. A few examples of waves are radio waves, microwaves, ultraviolet waves, etc. Earthquakes are also a type of mechanical wave known as seismic waves. The comprehensive elucidation of waves, five properties of waves, and simple harmonic motion is given below.

What are waves?

• Waves are the disturbances that travel in a medium from one point of a medium to another symmetrically in a given amount of time.
• The sound waves (mechanical waves) need a medium to travel or pass through, whereas electromagnetic waves, such as light, do not require a medium to travel. Light waves are capable of travelling through a vacuum.
• The waves are basically of two types – Longitudinal waves and Transverse waves.
• Sound waves are longitudinal waves that comprise rarefaction and compressions alternatively.
• Transverse waves emerge on the surfaces, such as water waves, which travel in an up and down manner. The crest is the highest point of a transverse wave, whereas the trough is the lowermost point of the transverse wave.
• Wavelength is the total distance between two consecutive crests and troughs.
• The velocity/speed of a wave is given by the equation – speed = wavelength*frequency.

Properties of waves

The five important properties of waves are Amplitude, Frequency, Wavelength, period, and Speed. Listed below is a detailed view of all the properties.

1.Amplitude (Property 1)

• Amplitude is among the first properties of waves and is denoted by the symbol ‘A,’ .
• Its S.I. unit is a metre (m).
• It is defined as the total displacement of a wave from Its resting position or simply the height of the wave from the centre of the imaginary line on which the wave is travelling.
• It can also be stated as the measure of intensity or the strength of the wave. For instance, if we consider sound waves, loudness measures the amplitude.
• The formula for calculating the amplitude of a wave is x = A sin (wt + Φ) OR x = A cos (wt + Φ), where x denotes the displacements of wave in metres, A denotes amplitude, w represents the angular frequency, and Φ indicates the phase difference.

2.Frequency (Property 2)

• The second property of waves is the frequency denoted by the symbol ‘f,’ The Greek symbol is lambda (𝛎), called nu.
• Its S.I. unit is Hertz (Hz), named in honour of a German Physicist – Heinrich Rudolf Hertz.
• It measures the total number of waves passing through a definite point in a given period.
• Frequency is inversely proportional to the period and is given by the formula f=1/T.
• The relation between wavelength, speed, and frequency can be determined by – f=v/ λ.
• In the case of an electromagnetic wave that propagates via vacuum, the v is replaced by c (speed of light), and the formula changes to f=c/ λ.
• A stroboscope is an instrument used to measure the frequency of a vibrating or rotating object. Frequency counters measure very high frequencies.
• The frequency of the red colour of the visible region is 400 THz, whereas the violet colour is 800 THz.
• The infrared waves, invisible to the human eye, have a frequency of less than 4*1014 Hz.

3.Wavelength ( Property 3)

• The wavelength is the third property of waves. It is the total displacement or distance between two corresponding troughs or crests.
• It is denoted by the Greek symbol lambda (λ).
• Its S.I. unit is a meter (m).
• It depends on the medium (water, air, or vacuum) through which it propagates.
• Spectrum is the range of frequencies and wavelengths. Different kinds of the spectrum are a sound spectrum, vibration spectrum, electromagnetic spectrum, etc.
• The wavelength of ultraviolet rays ranges from 100-400 nm, while the infrared region ranges between 780 – 1 nm.
• A wavemeter is used to measure single-wavelength radiation, such as monochromatic light.
• A wave packet is an envelope that describes the total amplitude.
• The formula for calculating wavelength is wavelength = wave velocity/frequency.

4.Time period (Property 4)

• The time period is the fourth property of waves and is defined as the time a particle of a medium takes to make a whole vibrational cycle.
• The time taken by two consecutive rarefaction and compressions to pass through a specific point can also be called the time period.
• Its S.I unit is seconds (s).
• The frequency and time period are inversely related, T=1/f; if frequency increases, the time period decreases, and vice versa. Here, T represents the time period, and f denotes frequency.

5.Speed/Velocity (Property 5)

• Speed id, the fifth property of a wave, is defined as the total distance covered by a point on the wave in a specific period of time.
• The S.I. unit of speed is metres per second (ms-1).
• A speedometer is an instrument used to measure the speed, usually fixed with another instrument, an odometer, which measures the distance travelled.
• It depends on the medium through which the wave is propagating.
• The speed of sound in air is 343 metres per second, and that of light is 29979248 m/s.
• The formula for calculating the speed of a wave is speed = Wavelength*frequency.

Simple harmonic motion (SHM)

• It is the back and forth or the repetitive movement of a particle through Its central position in which the restoring force is directly proportional to the displacement of the body from its mean position.
• A simple example of the simple harmonic motion is the vibration of a mass or Bob attached vertically to a fixed spring.
• The maximum displacement (-x) is the position under the most significant tension, which is the force responsible for the upward movement of the mass connected to the spring.
• Spring reaches maximum compression at maximum displacement (-x), which again forces the bob or the mass in the backward or downward direction.
• The object is directed towards the centre or the equilibrium position in both cases.
• At the equilibrium position, the acceleration is zero, and velocity is maximum.
• Musical instruments use such motion; that is why the name is harmonic motion which eventually causes vibrations in sound-producing waves to reach our ears in the form of music.
• Hooke’s law equation states that F = -Kx where f symbolises force, x is the displacement, and k represents constant.

Conclusion

The following article discusses the properties of waves. Waves are the disturbances that travel in a medium from one point of a medium to another symmetrically in a given amount of time. The five important properties of waves are amplitude, frequency, wavelength, period, and speed. When there is a total wave displacement from its resting position, it is known as amplitude. Frequency is the measure of the total number of waves passing through a definite point in a given period. Wavelength is the total displacement or distance between two corresponding troughs or crests. The time period of a wave is defined as the time a particle of a medium takes to make a whole vibrational cycle. The speed of a wave is defined as the total distance covered by a point on the wave in a specific period of time. Simple harmonic motion is the back and forth or the repetitive movement of a particle through its central position so that the displacements on either side of the position remain equal. This article is beneficial for the students preparing for NEET or JEE main entrance exams.