A disturbance in a medium that carries energy without total movement of the particles is known as a wave. It may have a form of pressure variation, elastic deformation, electric potential, magnetic or electric intensity or temperature.
What are Waves?
Waves are basically a disturbance that transmits energy in a medium without causing total movement of the particles present in that medium. A wave generally includes a periodic, monotonous movement.
A wave can be longitudinal or transverse in nature, but it depends on the direction of its oscillation. Like when disturbance causes the oscillations perpendicular to the propagation, then transverse waves occur; on the other hand when the oscillations are parallel to the direction of propagation, then longitudinal waves occur. However, mechanical waves can be both transverse as well as longitudinal. For instance, the sound is a longitudinal wave, and all electromagnetic waves are transverse in nature. The explanation of waves is strictly related to their physical origin for each detailed occurrence of a wave process.
Properties of Waves
The major properties of waves are:
- Amplitude – A wave is an energy propagation phenomenon where the height of the wave is called amplitude, which is usually measured in metres.
- Wavelength – In the adjacent cycles of wave crests, the distance between identical points is called a wavelength. It is also measured in metres.
- Period – The time required by a particle on a medium to complete one vibrational cycle is known as the period of a wave. The period is measured in time units, such as seconds or minutes.
- Frequency – The frequency of a sinusoidal wave can be defined as the number of complete oscillations per unit of time made by any wave element.
By the above mentioned frequency definition, we can know that if a body is in periodic motion, it has experienced one cycle after passing through a sequence of events or positions and recurring to its original state. Thus, frequency is a parameter that defines the rate of oscillation and vibration. The relation between the frequency and the period is given by the equation:
f=1/T
- Speed – The distance travelled by a given point on the wave (crest) in a given interval of time is the speed of a wave. That is Speed = Distance/Time.
- Angular frequency – The angular frequency refers to the angular displacement of any element for a sinusoidal wave; it is denoted by ω. Angular frequency formula and SI unit are given as:
ω = 2 π/T
Where,
- ω denotes the angular frequency of the wave
- T denotes the time period of the wave
- f denotes the ordinary frequency of the wave
Types of waves
- Transverse waves
- Mechanical wave
- Electromagnetic waves
- Longitudinal waves
- Electromagnetic waves
- Matter waves
Relation between Wavelength and Frequency
As we know, in a medium, the time required by a particle to complete one series of vibrations is known as the period (T) of a wave. it can be expressed as,
f = 1 / T
After one period, every point on the wave returns to the same value and since a wave experiences one oscillation during one period.
And the distance travelled by a wave per unit of time is known as the wave speed (v). Then, to calculate the distance travelled by one wavelength in one period of time, we can do it by the mathematical expression given below:
ν=λ/T
As we know that T = 1/f, hence the above equation can be further expressed as:
v = f λ
This means that the wave speed is equal to the product of its wavelength and frequency, which eventually is the relationship between wavelength and frequency.
Relation between velocity and wavelength
The product of frequency and wavelength for any given wave gives the velocity. Mathematically, the relationship between velocity and wavelength can be written as:
V = f x λ
Where,
- V denotes the velocity of the wave (m/s)
- f denotes the frequency of the wave (Hz)
- λ denotes the wavelength of the wave (m)
