Waves and Light: Light

Properties of Light

Light is a form of electromagnetic wave, which travels through space at a constant speed, referred to as the speed of light (approx. 3.00 x 10^8 m/s).
It can be described through its different properties such as wavelength, frequency and speed, which are all interrelated.
Light can exhibit both wave-like and particle-like properties. This dual nature is a fundamental concept in quantum physics known as wave-particle duality.

The wave properties of light can be exhibited through phenomena such as interference, diffraction and polarisation.
Interference occurs when two or more waves superpose to create a new wave.
Diffraction is observed when light passes through a narrow gap or around an object, causing it to spread out.
Polarisation refers to the orientation of the oscillations in a transverse wave.

The particle-like nature of light can be observed in phenomena such as the photoelectric effect and Compton’s scattering.
These phenomena suggest that light behaves as though it’s composed of small packets or particles called photons.
The photoelectric effect involves light striking a metal surface, causing the ejection of electrons from the metal.

Light can interact with matter in several ways such as absorption, reflection, refraction and transmission.
Absorption is when matter captures electromagnetic radiation and transforms it into internal energy.
Reflection is when light bounces off an object, while refraction is the change in direction of light as it passes from one medium to another.
Transmission is the passage of light through a material.

Spectroscopy helps us understand light’s interaction with matter by studying the spectrum of light.
The line emission spectrum of an element is unique and can be used to identify the element.
An absorption spectrum shows the range of light wavelengths absorbed by a substance.