Electromagnetic spectrum Flashcards
What are all electromagnetic waves?
Transverse waves that travel at the same speed (or velocity) in a vacuum.
What is the order of electromagnetic waves from highest frequency to lowest?
Gamma X-ray Ultraviolet Visible Infrared Microwave Radio
As you move from gamma rays to radio waves what happens to the wavelengths?
Wavelengths increase
As you move from the gamma rays to radio waves, what happens to the frequencies?
Frequencies decrease
What do electromagnetic waves transfer?
They transfer energy from the source of the wave to an absorber of the wave.
Gamma rays carry the most ____ of all the electromagnetic waves.
Energy
What are gamma rays used for?
Medical imaging and therapy, astronomy, sterilisation and food preservation.
What are the risks of gamma ray usage?
Gamma rays are extremely penetrating and damaging to living tissues and cells.
What can we use gamma rays to destroy?
Bacteria and tumours
What can X-rays penetrate?
Soft materials (like body tissue). - Bones are dense materials that absorb X-rays. We can use X-rays to build a shaded image of bones and body tissue.
What are X-rays used for?
Medical and industrial imaging, to treat cancer and for security purposes to detect weapons in airports (and other places)
X-rays are highly _____?
Ionising
What does highly ionising mean?
Can damage body cells
What are the safety precautions when dealing with X-rays?
Minimum exposure, appropriate shielding
Where is ultraviolet light on the spectrum?
Between X-rays and visible light
What happens atomically in UV lamps?
In lamps, UV photons excite (gives energy to) atoms. The atoms then release visible light.
What are the risks of UV light?
Exposure to too much ultraviolet light can cause skin burns, skin cancer and cataract formations in the eye.
What is Ultraviolet light used for?
medical and forensic photography, air purification, disinfection and medical therapy and to detect fake bank notes
What are the risks of Infra-red radiation?
serious skin burns if emitted from high-intensity sources.
What is infra-red radiation used for?
TV controls, security purposes –> intruder alarms by detecting body heat.
How is infra-red used to cook food?
The frequency is high enough to excite particles in food. This increases their temperature.
What are microwaves used for?
Satellite communications, transmit signal from a nearby phone mast to a mobile phone.
Why are microwaves useful for cooking food?
Microwaves are absorbed by water, heating up the water in the process. This makes microwaves useful for cooking food because food contains lots of water.
How to microwaves travel through the atmosphere?
In straight lines. This makes them good for transmitting signals.
