Electromagnetic Waves | Waec Physics

Electromagnetic Waves

1. Electromagnetic waves are transverse waves consisting of oscillating electric and magnetic fields.
2. They do not require a medium and can propagate through a vacuum.
3. The speed of electromagnetic waves in a vacuum is $3 \times 10^8m/s$.
4. Electromagnetic waves transfer energy and momentum.
5. The wave properties include wavelength ($\lambda$), frequency ($f$), and speed ($c$), related by $c = f\lambda$.
6. Electromagnetic waves exhibit reflection, refraction, diffraction, and interference.
7. They carry energy in the form of electromagnetic radiation.
8. Electromagnetic waves can be polarized, demonstrating their transverse nature.
9. They are produced by accelerating charged particles.
10. The spectrum of electromagnetic waves includes a wide range of wavelengths and frequencies.
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Types of Radiation in the Electromagnetic Spectrum

11. The electromagnetic spectrum is the range of all electromagnetic wave frequencies and wavelengths.
12. It includes radio waves, microwaves, infrared radiation, visible light, ultraviolet rays, X-rays, and gamma rays.
13. Each type of radiation has unique properties and applications.
14. The spectrum is arranged in increasing order of frequency and decreasing wavelength.
15. Radio waves have the longest wavelength and lowest frequency.
16. Gamma rays have the shortest wavelength and highest frequency.
17. Visible light is the only part of the spectrum detectable by the human eye.
18. The energy of electromagnetic waves increases with frequency.
19. The spectrum is continuous, with no distinct boundaries between types.
20. Applications of the spectrum span communication, medicine, and technology.
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Elementary Description and Uses of Radiation

Radio Waves

21. Radio waves have the longest wavelengths, ranging from millimeters to kilometers.
22. They are used in communication systems, including radio, television, and mobile phones.
23. Radio telescopes use radio waves to study astronomical objects.
24. AM and FM radio frequencies fall within the radio wave range.
25. Radio waves are essential for satellite communication and GPS systems.
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Microwaves

26. Microwaves have shorter wavelengths than radio waves, ranging from 1 mm to 1 m.
27. They are used in cooking (microwave ovens) and radar systems.
28. Microwaves are critical in wireless communication and Bluetooth technology.
29. They penetrate through clouds and fog, enabling satellite imaging.
30. Astronomers use microwaves to study cosmic background radiation.
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Infrared Radiation

31. Infrared (IR) radiation has wavelengths slightly longer than visible light, ranging from 700 nm to 1 mm.
32. Infrared is emitted by warm objects and is associated with heat.
33. Infrared cameras are used in thermal imaging and night vision.
34. IR radiation is used in remote controls, sensors, and data transmission.
35. It is also used in medical therapies and detecting heat leaks in buildings.
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Visible Light

36. Visible light is the range of wavelengths detectable by the human eye, approximately 400–700 nm.
37. It enables vision and is essential for photosynthesis in plants.
38. Visible light is used in optical devices like microscopes, telescopes, and cameras.
39. It is also used in lasers, lighting, and optical communication.
40. The colors of visible light (ROYGBIV) are produced by varying wavelengths.
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Ultraviolet Radiation

41. Ultraviolet (UV) radiation has wavelengths shorter than visible light, ranging from 10 nm to 400 nm.
42. It is responsible for causing sunburn and producing vitamin D in the skin.
43. UV rays are used in sterilization, water purification, and forensic analysis.
44. Prolonged exposure to UV radiation can damage the skin and eyes.
45. UV light is used in detecting counterfeit currency and in tanning lamps.
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X-Rays

46. X-rays have wavelengths ranging from 0.01 nm to 10 nm.
47. They are used in medical imaging to view bones and internal structures.
48. X-rays are used in airport security for scanning luggage.
49. High-energy X-rays are used in cancer treatment and material analysis.
50. X-ray telescopes study high-energy cosmic phenomena like black holes and supernovae.
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Gamma Rays

51. Gamma rays have the shortest wavelengths, less than 0.01 nm, and the highest energy.
52. They are emitted during radioactive decay and nuclear reactions.
53. Gamma rays are used in cancer treatment (radiotherapy) and sterilization.
54. Astronomers use gamma rays to study extreme cosmic events like gamma-ray bursts.
55. Gamma radiation is also used in industrial testing for detecting material flaws.
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General Properties and Applications

56. All electromagnetic waves travel at the same speed in a vacuum but vary in frequency and wavelength.
57. The energy of waves increases as the wavelength decreases.
58. Electromagnetic waves enable wireless communication across vast distances.
59. Advances in medical imaging rely on X-rays, CT scans, and gamma radiation.
60. Understanding the spectrum supports developments in astronomy, security, and environmental monitoring.

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