Electromagnetic Wave and Spectrum

Also called

electromagnetic wave · electromagnetic spectrum · oscillating charge · electric field · magnetic field · transverse wave · speed of light · radio waves · microwaves · infrared · visible light · ultraviolet · X-rays · gamma rays · microwave oven · wavelength and frequency · Maxwell · विद्युत चुंबकीय तरंग · विद्युत चुंबकीय स्पेक्ट्रम · प्रकाश की चाल

Topics

• An accelerating charge radiates: a charge oscillating up and down on an antenna sends out an electromagnetic wave.
• The wave carries an oscillating electric field E and magnetic field B that are in phase: they peak together.
• E and B are perpendicular to each other and to the direction of travel, so the wave is transverse.
• In vacuum every electromagnetic wave travels at c = 1/√(μ₀ε₀) ≈ 3 × 10⁸ m/s, and E₀ = cB₀.
• Electromagnetic waves need no medium; they carry energy and momentum through empty space.
• The spectrum runs from radio waves (longest wavelength) through microwaves, infrared, visible light…
• Frequency and wavelength are linked by c = fλ: the shorter the wavelength, the higher the frequency and photon energy.
• A microwave oven uses waves of about 2.45 GHz that make water molecules flip to and fro, heating the food.
• Radio and TV use radio waves, remote controls use infrared, sunburn comes from ultraviolet, and X-rays image bones.

About this model

A GLB file of about 845 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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