EM Spectrum (Full)
Year 10 (IGCSE) 🌊 Waves & Optics Describe properties, uses and hazards of all EM spectrum regions.
🌈 The Complete Electromagnetic Spectrum
The EM spectrum is a continuum of all electromagnetic waves, ordered by wavelength or frequency.
| 📡 Wave | 📏 Wavelength | 📊 Frequency (Hz) | ⚡ Energy |
|---|---|---|---|
| 📻 Radio | 1 mm → 100 km+ | 10³ → 10¹² | Lowest |
| 📱 Microwave | 1 mm → 30 cm | 10⁹ → 3×10¹¹ | ↓ |
| 🌡️ Infrared | 700 nm → 1 mm | 3×10¹¹ → 4×10¹⁴ | ↓ |
| 👁️ Visible | 400 → 700 nm | 4×10¹⁴ → 8×10¹⁴ | ↓ |
| 🔆 UV | 10 → 400 nm | 8×10¹⁴ → 3×10¹⁶ | ↓ |
| ☢️ X-ray | 0.01 → 10 nm | 3×10¹⁶ → 3×10¹⁹ | ↓ |
| ☢️ Gamma | < 0.01 nm | > 3×10¹⁹ | Highest |
📡 Properties, Uses and Sources
All EM waves share key properties: transverse, travel at c = 3×10⁸ m/s in vacuum, can be reflected, refracted, diffracted.
| 📡 Wave | ✅ Key Uses | 🔋 Source |
|---|---|---|
| Radio | Broadcasting, satellite comm., MRI | Radio transmitters, stars |
| Microwave | Cooking, 4G/5G, satellite navigation | Microwave generators |
| Infrared | Thermal cameras, remote controls, optical fibres | Warm objects |
| Visible | Vision, photography, photosynthesis | Hot objects, LEDs, stars |
| UV | Tanning, sterilisation, banknote security | Sun, UV lamps |
| X-ray | Medical imaging, airport security, crystallography | X-ray tubes |
| Gamma | Cancer radiotherapy, sterilising food, tracer studies | Radioactive nuclei |
⚠️ Ionising Radiation and Safety
X-rays and gamma rays are ionising — they have enough energy to remove electrons from atoms, potentially damaging DNA.
Ionising radiation hazards: High doses cause radiation sickness, cell death, and cancer. Long-term low doses increase cancer risk. Always follow the three protection principles: time (minimise), distance (maximise), shielding (lead/concrete).
| 🌊 Wave type | ⚡ Ionising? | 🛡️ Shield |
|---|---|---|
| Radio, microwave, IR, visible | ❌ No | Not needed (below threshold) |
| UV | ✅ Weakly (at high dose) | Sunscreen, clothing |
| X-ray | ✅ Yes | Lead aprons, lead glass |
| Gamma | ✅ Yes (most penetrating) | Thick lead or concrete |
Ready to test yourself? Click the Quiz tab above to answer questions on this topic!
🌈 EM Spectrum Wave Calculator
All EM waves travel at c = 3 × 10⁸ m/s in a vacuum. Use v = fλ.