The Electromagnetic Spectrum

The Electromagnetic Spectrum

The electromagnetic spectrum is a family of waves.

Radio waves, visible light, X-rays and gamma rays are all members of the same electromagnetic family.

They mainly differ in frequency and wavelength.

The Electromagnetic Spectrum

The electromagnetic spectrum is the complete range of electromagnetic waves arranged according to wavelength or frequency.

All electromagnetic waves consist of changing electric and magnetic fields and can travel through a vacuum.

In vacuum, all electromagnetic waves travel at approximately:

**c = 3.0 × 10⁸ m/s**

Order of the Spectrum

From longest wavelength and lowest frequency to shortest wavelength and highest frequency:

Radio → Microwave → Infrared → Visible → Ultraviolet → X-rays → Gamma rays

Frequency and Wavelength

Wave speed is given by:

**c = fλ**

where:

`c` = speed of electromagnetic waves in vacuum `f` = frequency `λ` = wavelength

Since `c` is constant in vacuum:

higher frequency → shorter wavelength

lower frequency → longer wavelength

Energy

For electromagnetic radiation:

**E = hf**

where:

`E` = photon energy `h` = Planck's constant `f` = frequency

Therefore:

higher frequency → greater photon energy

Shared Properties

All electromagnetic waves:

can travel through vacuum; carry energy; travel at the same speed in vacuum; can show reflection, refraction, diffraction and interference.

The Electromagnetic Spectrum — Advanced

The spectrum is continuous rather than divided into absolute natural boundaries. The named regions are convenient bands based on wavelength, frequency and common physical interactions.