Electromagnetic Waves and Spectrum
Nature of electromagnetic waves, transverse electric and magnetic fields, speed in vacuum c = 1/√(μ₀ε₀) = 3 × 10⁸ m/s, electromagnetic spectrum classification, and practical applications.
Marking a lesson complete represents finishing your study of the topic; it does not denote tested mastery.
Learning Objectives
- Describe the transverse electromagnetic wave model and the perpendicular oscillations of electric and magnetic fields.
- Identify the regions of the electromagnetic spectrum in order of frequency and wavelength with practical applications and hazards.
Core Theory & Concepts
Electromagnetic waves are self-propagating transverse oscillations of mutual electric and magnetic fields in space, requiring no material medium and traveling in vacuum at the universal speed c = 3.0 × 10⁸ m s⁻¹.
Speed of Electromagnetic Radiation
In vacuum, c = 1 / √(μ₀ ε₀) = 2.998 × 10⁸ m s⁻¹. For all regions of the spectrum: c = f λ.
The Complete EM Spectrum
Arranged by increasing frequency (decreasing wavelength): Radio waves (> 1 m) → Microwaves (1 mm – 1 m) → Infrared (700 nm – 1 mm) → Visible light (400 nm – 700 nm) → Ultraviolet (10 nm – 400 nm) → X-rays (0.01 nm – 10 nm) → Gamma rays (< 0.01 nm).
Common Misconceptions
Gamma rays travel faster than radio waves in vacuum because they have much higher frequency.
Syllabus Topic Outline
- 1Generation and propagation of electromagnetic waves
- 2Speed of light c = 3.0 × 10⁸ m s⁻¹ and wave equation c = fλ
- 3Electromagnetic spectrum: Radio, Microwaves, Infrared, Visible, Ultraviolet, X-rays, Gamma rays
- 4Atmospheric transmission windows and greenhouse effect