Cheat sheet · Class 12 · CBSE · Science Physics
Electromagnetic Waves cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 12 · Physics
Cheat sheet
Chapter 8Electromagnetic Waves
Radio, Micro, IR, Visible, UV, X, Gamma — “Raging Martians Invaded Venus Using X-ray Guns”.
1. Properties
- Produced by accelerated charges.
- E and B oscillate ⊥ to each other and to propagation.
- Transverse; need no medium.
Displacement current (Maxwell).
2. EM Spectrum
| Wave | Wavelength | Use |
|---|---|---|
| Radio | 0.1 m | broadcasting |
| Microwave | 1 mm – 0.1 m | radar, ovens |
| Infrared | 700 nm – 1 mm | remote controls, heating |
| Visible | 400–700 nm | vision |
| Ultraviolet | 1–400 nm | sterilisation |
| X-rays | 0.01–10 nm | medical imaging |
| Gamma rays | < 0.01 nm | cancer treatment |
3. Key Points
- EM waves carry energy and momentum.
- Ozone absorbs UV.
- Greenhouse effect involves IR.
- Hertz first produced EM waves.
Remember: Displacement current | c = 1/√(μ₀ε₀) | spectrum order
Electromagnetic Waves: questions and notes
More Class 12 · CBSE · Science Physics cheat sheets
- Electric Charges and Fields
- Electrostatic Potential and Capacitance
- Current Electricity
- Moving Charges and Magnetism
- Magnetism and Matter
- Electromagnetic Induction
- Alternating Current
- Electromagnetic Waves
- Ray Optics and Optical Instruments
- Wave Optics
- Dual Nature of Radiation and Matter
- Atoms
- Nuclei
- Semiconductor Electronics
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