The Electromagnetic Spectrum

This lesson covers the electromagnetic (EM) spectrum — the full range of electromagnetic waves — as required by the Edexcel GCSE Physics specification (1PH0), Topic 4: Waves. You need to know the order of the spectrum, the properties shared by all EM waves, and the approximate wavelength and frequency ranges.

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What Are Electromagnetic Waves?

Electromagnetic (EM) waves are waves that consist of oscillating electric and magnetic fields. They are fundamentally different from mechanical waves (such as sound) because they do not require a medium to travel through.

Properties Shared by All EM Waves

• All EM waves are transverse waves.
• All EM waves travel at the speed of light in a vacuum: v = 3 × 10⁸ m/s.
• All EM waves transfer energy from a source to an absorber.
• All EM waves can travel through a vacuum (they do not need a medium).
• All EM waves can be reflected, refracted, and absorbed.
• All EM waves obey the wave equation: v = f × λ.