Waves and Light: The Nature of Waves

Introduction to Waves

A wave is a disturbance that transfers energy from one point to another without transferring matter.
Waves can be classified into two main types: transverse waves and longitudinal waves.
In transverse waves, the displacement is perpendicular to the direction of the wave’s propagation, while in longitudinal waves, it is parallel.
Examples of transverse waves include light and other forms of electromagnetic radiation, while sound waves are an example of longitudinal waves.
Waves carry information and energy but do not transfer particles in the medium they travel through.

The amplitude is the maximum displacement of a wave, representing its energy.
Frequency is the number of complete cycles or vibrations per unit time, measured in Hertz (Hz).
The wavelength is the shortest distance between points where the wave pattern repeats itself, such as from crest-to-crest or trough-to-trough.
Speed of a wave is the rate at which the wave propagates in a certain direction.
Phase describes the position in the wave cycle at any particular time.
Polarisation is a property of waves that describes the orientation of their oscillations.
Interference is the process by which two waves combine to form a resultant wave of greater, lower, or the same amplitude.

Light waves are transverse waves in nature and make up part of the electromagnetic spectrum.
They travel at a speed of approximately 3.0 x 10^8 m/s in a vacuum.
Visible light has a wavelength range of approximately 400nm (violet) to 700nm (red).
Light can be diffracted, refracted, reflected, and undergo interference, demonstrating its wave-like properties.

Wave-particle duality is the concept that all particles exhibit both wave and particle properties.
Light is an example of a particle that also exhibits wave-like properties, this is known as the dual nature of light.
Photons are the ‘particle’ elements of light. They can be thought of as a wave packet of light energy, and each has energy proportional to the light wave’s frequency.
The wave behaviour of particles was first proposed by Louis de Broglie based on Einstein’s work combining theories of relativity and quantum mechanics.

The behaviour of particles at the quantum level can be quite different from macroscopic objects.
As per the Heisenberg’s uncertainty principle, the position and the velocity of a particle cannot both be accurately determined at the same time.
In quantum mechanics, light is sometimes described as a wave and other times as a stream of photons. This has given rise to the wave-particle duality concept.