Electromagnetic Waves-5 Flashcards
What’s the EM spectrum
Radio waves - Biggest wavelength - smallest frequency
Micro waves
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays - smallest wavelength - biggest frequency
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Are EM waves transverse or longitudinal
Transverse
How do the different waves vary in speed
They all travel at the same speed through a vacuum but at different speeds in different materials.
How are EM waves generated
By a variety of changes in atoms and their nuclei, giving a large range of frequencies.
Give the order of colours on the EM spectrum
Longest- shortest wavelength.
Red, orange, yellow, green, blue, indigo, violet.
All EM waves transfer energy from a _______ to an ________.
E.g. when you warm yourself by an electric heater, infrared waves transfer _________ from the thermal energy store of the ________ (the source) to your thermal energy store (the absorber)
Source, absorber, energy, heater
Visible light
Part of spectrum our eyes can detect. Light bulbs emit it and cameras detect it.
Infrared
Communication at short ranges (tv to remote control or between computers in same room).
Grill or toaster
Thermal imaging
Security systems
Dangers: Too much can kill cells causing burns to the skin + damage cells
Microwaves
Communications and satellite transmissions (mobile phone signals)
Microwaves transfer energy to food
Dangers: heat body cells from the inside
Radiowaves
Transmitting radio broadcasts and TV programmes. Some via satellites.
Controllers on ground communicate with spacecraft using radio waves
Ultraviolet
Absorbed by skin
Can kill microorganisms in water
Dangers: Sunburn and damage DNA. Can cause skin cancer. Can damage eyes.
Fluorescence
Materials that absorb ultraviolet radiation and re-emit it as visible light.
X rays
Can pass through fat and muscle easily but are absorbed by bones so are good for making medical imaging in the body.
Security scanners at airports.
Dangers: Can penetrate the body. Excessive exposure can cause mutations in DNA that kill cells and cause cancer.
Gamma rays
Sterilise food and surgical instruments by killing microorganisms
because they transfer a lot of energy and can kill cells.
Kill cancer in radiotherapy.
Used to detect cancer by injecting chemical that emits gamma rays is injected into the blood and collects in cancer cells and is then detected by scanner.
Dangers: Can penetrate the body. Excessive exposure can cause mutations in DNA that kill cells and cause cancer.
What’s EM radiation caused by?
Changes in the electrons or nuclei of the atoms (when they’re heated, changes in the way electrons are arranged can produce infrared radiation or visible light. Changes in nuclei in the atom produces gamma radiation.
