Electromagnetic Waves

Introduction to Electromagnetic Waves

  • Electromagnetic waves are a type of wave that can travel through the vacuum of space.
  • They are waves of energy that spread outwards from an originating source.
  • Electromagnetic waves consist of oscillating electric and magnetic fields, which are perpendicular to each other and the direction of travel of the wave.
  • Important characteristics of electromagnetic waves include their wavelength, frequency, and speed.

The Electromagnetic Spectrum

  • The electromagnetic spectrum is an arrangement of electromagnetic waves according to their wavelengths and frequencies.
  • Its ranges include, from longest wavelength to shortest: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
  • Visible light is a small part of the spectrum, which human eyes are sensitive to. It includes all the colours that we can see, from red (longest wavelength) to violet (shortest wavelength).
  • Different parts of the electromagnetic spectrum have different impacts, uses, and hazards due to their different energy levels.

Interaction with Matter

  • When electromagnetic waves encounter matter, they can be reflected, absorbed, or transmitted.
  • The behaviour of the electromagnetic wave depends on the type of material and the frequency of the wave.
  • For example, visible light is reflected by a mirror, absorbed by an opaque object, and transmitted by clear materials like glass or air.

Tracking the Speed of Light

  • In a vacuum, all electromagnetic waves travel at the same speed — the speed of light.
  • The speed of light, represented as ‘c’, is approximately 3 x 10^8 metres per second.
  • Despite their different wavelengths and frequencies, all types of electromagnetic waves maintain this speed.

Understanding electromagnetic waves and their properties is essential, as they have a multitude of applications. These range from microwave ovens and radio broadcasting to medical imaging with X-rays and treatment with radiation therapy.