The Electromagnetic Spectrum (College Board AP® Chemistry)

The Electromagnetic Spectrum

• The electromagnetic spectrum is a range of frequencies that includes all wavelengths of electromagnetic radiation

• The spectrum connects three important variables in the study of light: frequency, wavelength and energy

  • Wavelength is the distance between two consecutive crests on a wave

  • Frequency is how many waves occur per second

• The higher energy radiations correspond to the shorter wavelengths

  • High energy and high frequency radiation is very damaging for living beings

The electromagnetic spectrum diagram

The electromagnetic spectrum spans a broad spectrum from very long radio waves to very short gamma rays

• All the light waves travel at the same speed, the only thing that is different is their frequencies

• The speed of light (c) is a constant and it has a value of 998 x 10⁸ ms^-1

• Molecules behave in particular ways when they are exposed to radiation of different frequencies

  • When exposed to microwaves, molecules will rotate

  • When exposed to infrared radiation, molecules will vibrate

  • When exposed to ultraviolet or visible radiation, the electrons will jump between energy shells