Waves: Electromagnetic Waves

• Waves: Electromagnetic Waves

1. All electromagnetic waves travel at a speed of 300,000 kilometres per second (the speed of light) in a vacuum.

2. They are transverse waves, meaning their oscillations are perpendicular to the direction of energy transfer.

3. The electromagnetic spectrum includes, in order from lowest energy/frequency/wavelength to highest: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

4. No medium (matter) is required for electromagnetic waves to propagate. They can move through a vacuum, such as space.

5. Radio waves have the longest wavelengths and lowest frequencies of the electromagnetic spectrum, leading to uses like broadcasting and communication.

6. Microwaves have somewhat shorter wavelengths and higher frequencies than radio waves, allowing them to be used for things like satellite communications and heating food.

7. Infrared radiation has even shorter wavelengths and higher frequencies, which makes it useful for heaters and night vision devices.

8. Visible light, perceived by human eyes, has a relatively small range of wavelengths and frequencies in the electromagnetic spectrum.

9. Ultraviolet rays have shorter wavelengths and higher frequencies than visible light, which leads to applications like sterilisation and tanning but also harmful effects like skin burns and cancer.

10. X-rays and gamma rays are at the extreme end of the spectrum, with the shortest wavelengths and highest frequencies, they are used in medical imaging and radiotherapy but can be highly harmful if not used correctly.

11. The reflexion, refraction and diffraction of electromagnetic waves obey the same general principles as those for waves in matter.

12. Energy carried by an electromagnetic wave can be transformed into other forms of energy, depending on the wave’s frequency and the material it’s interacting with.

Remember to practise questions on each of these points to enhance your understanding and recall of the topic.