CHAPTER 14: THE ELECTROMAGNETIC SPECTRUM

Light, radio waves, X-rays, and the heat from a fire are all the same phenomenon—electromagnetic waves. They are oscillations of electric and magnetic fields that travel through space at the speed of light. The only difference between them is their wavelength and frequency. This chapter explores the entire electromagnetic spectrum, from the longest radio waves to the shortest gamma rays, and reveals how each type of wave is produced, detected, and used in technology, medicine, and everyday life.

14.1 PROPERTIES OF ELECTROMAGNETIC WAVES

All electromagnetic (EM) waves share fundamental properties, regardless of their wavelength or frequency.

14.1.1 Transverse Nature

Electromagnetic waves are transverse waves. This means the oscillations of the electric and magnetic fields are perpendicular to the direction of energy transfer. The electric field and magnetic field oscillate at right angles to each other and to the direction of wave propagation.

14.1.2 Speed of Light

In a vacuum, all electromagnetic waves travel at the same speed:

c = 3.0 × 10⁸ m/s

This is known as the speed of light in a vacuum. In air, the speed is slightly less, but for most purposes, we use the same value. In other transparent materials (glass, water), the speed is significantly reduced, causing refraction.

14.1.3 No Medium Required

Unlike mechanical waves (sound, water waves), electromagnetic waves do not require a medium to t