Part A · Spectrum, refraction and discovery Light and the electromagnetic spectrum mind map
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Spectrum
Common properties: Transverse; vacuum speed c ≈ 3 × 10⁸ m/s; no medium needed
Order: Radio → microwave → IR → visible → UV → X-ray → gamma
Visible colours: Red → violet; frequency rises, wavelength falls
Energy / matter: Photon energy rises with f; beam intensity / time also matter
Refraction
Glass: Slower → towards normal; emerging into air → away
Method: Trace block / ray marks; normals; protractor angles from normal
Accuracy: Repeat angles; sharp separated marks; same alignment
Parallel faces: Emergent ray parallel / displaced; f fixed, v and λ change
Safety: Ray box; protect eyes from beams
Beyond vision
Herschel: Thermometers beyond red warmed → infrared evidence
