AQA A Level Physics

Revision Notes

3.3.4 Developing Theories of EM Radiation

Developing Theories of EM Radiation

Isaac Newton (1672)

  • Newton proposed that visible light is a stream of microscopic particles called corpuscles
  • However, these corpuscles could not explain interference or diffraction effects, therefore, the view of light as a wave was adopted instead

Christiaan Huygens (1678)

  • Huygens came up with the original Wave Theory of Light to explain the phenomena of diffraction and refraction
  • This theory describes light as a series of wavefronts on which every point is a source of waves that spread out and travel at the same speed as the source wave
    • These are known as Huygens’ wavelets

Thomas Young (1801)

  • Young devised the famous double-slit experiment
  • This provided experimental proof that light is a wave that can undergo constructive and destructive interference

James Clerk Maxwell (1862)

  • Maxwell showed that electric and magnetic fields obeyed the wave equation. This means that light was simply waves made up of electric and magnetic fields travelling perpendicular to one another
  • Later, Maxwell and Hertz discovered the full electromagnetic spectrum

Albert Einstein (1905)

  • Einstein discovered that light behaves as a particle, as demonstrated by the photoelectric effect
  • He described light in terms of packets of energy called photons
  • Later the scientific community came to understand that light behaves both like a wave and a particle
    • This is known as wave-particle duality

Theories of EM radiation timeline(1), downloadable AS & A Level Physics revision notesTheories of EM radiation timeline(2), downloadable AS & A Level Physics revision notes

Author: Katie

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now
Already a member?
Go to Top