Electromagnetic waves

• All electromagnetic waves are transverse waves.
• Electromagnetic waves are made up of oscillating electric and magnetic fields. They do not carry electric charges.
• All electromagnetic waves can travel without a medium, with the same speed of (3 x 10^8 m/s) in a vacuum.
• The wave speed equation, v=fλ, applies to all electromagnetic waves.
• When an electromagnetic wave travels from a vacuum to other media, the wave speed and wavelength decrease. The decrease in speed is different for different frequencies. However, the frequency stays the same as the source when the wave gies into a different medium.
• Electromagnetic waves undergo reflections and refractions.
• Electromagnetic waves transfer energy.
• Ionising waves are those with higher frequencies and hence higher energies. They can eject electrons from atoms and molecules to create ions. The ions can cause harm by disrupting cell functions and even killing them.
• All material bodies emit a range of electromagnetic waves. In general, higher temperature bodies tend to emit more and higher frequency electromagnetic waves.
• 1. radiowaves (λ=3m, f=10^8Hz)
  2. microwaves (λ=3cm, f=10^10Hz)
  3. infrared (λ=10^-4m, f=10^12Hz)
  4. visible light (λ=6 x 10^-7m, f= 5x10^14Hz)
  5. ultraviolet (λ=10^-8m, f=3 x 10^16Hz)
  6. X-rays (λ=10^10m, f=3 x 10^18Hz)
  7. gamma rays (λ=10^-12m, f= 3 x 10^20Hz)
• Some uses of radio waves include radios, radio telescope, TV broadcast, and RFID tags.
• Some uses for microwaves are microwaves, wifi, communication such as GPS, satellite communication and radar, and cancer treatment.
• Some uses for Infrared are data transfer, heated rods, long-distance fibre-optic cables, remote controls, camera auto-focusing and thermometers and intruder alarms.
• Some uses of visible light are to take a photograph, optical fibres and leaf growth, to see.
• Some uses of ultraviolet are disinfection and sterilisation, produce vitamin D, anti-forgery features.
• Some uses of X-rays are treating cancer, detect bones and soft tissue, scan defects in mental parts, scan luggage for prohibited items. However, excessive use will make you at risk of cancer and cell damage.
• Some uses of gamma rays are radiotherapy, killing germs in food and sterilising medical equipment, detecting defects in manufacturing, and treat cancer.
• Ionising radiation is from high frequency electromagnetic waves like x-rays and gamma rays. It could result in cell death, mutations leading to diseases, organ failure and risk of cancer.