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Electromagnetic Radiation - Coggle Diagram
Electromagnetic Radiation
Types of Electromagnetic Rays:
Infrared
Visible
Microwave
Ultraviolet
Radio
X-ray
Gamma Ray
Note: Shorter wavelength = higher frequency (and vice versa)
Applications:
Visual light: Photos, videos, text and other form of visual communication, fibro optic cables and light emitting devices (e..g lamps, LEDs etc.)
Ultraviolet radiation: Barcode scanning, forensic analysis, DNA sequencing and sterilization of equipment.
Infrared radiation: Thermal imaging cameras, spectroscopy, weather forecasting and intruder alarms
X-rays: X-ray microscopy and crystallography, projectional radiography and radiation therapy.
Microwaves: Wireless networks, radar, satellite and spacecraft communications, microwave ovens and keyless entry devices
Gamma rays: Radiation therapy
Radio Waves: Over the air television, radio broadcasts, navigation, air traffic control and cellular telephony
Properties:
The wave speed equation (v = fλ) is applicable to all electromagnetic waves, where:
v = wave speed
f = frequency of the wave
λ = wavelength of the wave
Electromagnetic waves can transfer energy from one place to another (E.g. EM waves from the Sun transfer thermal energy to Earth)
Electromagnetic waves carry no charge
Electromagnetic waves are transverse waves comprising electric and magnetic fields oscillating at 90° to each other
Electromagnetic waves obey the laws of reflection and refraction (except for Gamma rays, which cannot be reflected by mirrors)
All electromagnetic waves travel at the speed of light through vacuum
When electromagnetic waves travel from one medium to another,
Speed and wavelength change
Frequency does not change
Electromagnetic waves can travel through vacuum (they do not need a medium to travel from one place to another)
Effects
Infrared heating is the transmission of heat through infrared radiation. We feel warm because our skin and clothes absorb infrared radiation. Some animals have used the property that hot things release infrared radiation and developed organs to sense the infrared radiation. One example of this is snakes, some of which have organs to sense infrared radiation. Using this organ, a blind snake can accurately strike at a heat emitting living prey and can detect prey by the infrared radiation they give off within a certain proximity.
Ionising radiation (UV Radiation, X-Rays and Gamma Rays) are radiation that has enough energy to remove electrons from atoms or molecules, thus creating ions. This process is called ionization. Ionizing radiation can damage biological molecules (e.g. proteins, DNA), leading to abnormal patterns of cell division. This may cause symptoms such as leukemia (cancer of the blood) and a developing foetus to become deformed.
The human brain uses pulses of electricity to control the body via nerve impulses. Excessive exposure to electromagnetic radiation can affect bodily rhythms. This is why houses near power stations (which emit large amounts of electromagnetic radiation) are avoided by people, as living near power stations can lead to nausea, insomnia and changes in the electroencephalogram (which measures electrical activity in the brain).
Long term exposure to ultraviolet radiation can lead to development of skin cancer. Application of sunscreen can reduce the effects by absorbing UV radiation before it enters our skin, or reflecting it, much like a mirror, before it enters our skin.
