GCSE Physics · Edexcel 1PH0 · Topic 5C
The electromagnetic spectrum
Key points
- EM waves are transverse, transfer energy from source to absorber and travel at m/s in a vacuum.
- Order of increasing frequency (decreasing wavelength): radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays.
- Uses: radio (broadcasting), microwaves (cooking, satellites), infrared (heaters, remote controls, thermal cameras), visible (fibre optics), UV (security marking, sterilising), X-rays (medical imaging), gamma (sterilising, cancer treatment).
- Dangers increase with frequency: microwaves heat cells, infrared burns skin, UV damages eyes and skin, X-rays and gamma are ionising and can cause mutations and cancer.
- Radio waves can be produced by oscillations in electrical circuits and can induce an alternating current in an aerial.
- Different wavelengths are absorbed, transmitted or refracted differently by materials.
Topic notesPremium
Radio waves, microwaves, light and X-rays are all the same kind of wave, differing only in wavelength and frequency. This sub-topic covers their shared properties, their uses, their dangers and how they are produced.
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