Electromagnetic Waves and Dangers of Electromagnetic Waves Flashcards
What are all EM waves?
Transverse waves, that transfer energy from a source to an absorber
What would all EM waves do in a vacuum or in the air?
Travel at the same speed
How are EM waves grouped?
Based on their wavelength and frequency, with INCREASING frequency and DECREASING wavelength
Name some uses of Radio Waves?
Mainly communication e.g radios
- They are used as they can travel long distances
before being absorbed.
Name some uses of Microwaves?
1) Communications between satellites
2) Microwave Ovens
Why are Microwaves used in Satelite communication?
They can easily pass through the earth’s atmosphere, without being reflected or refracted
Why are microwaves used to heat food?
They can heat up the water molecules in water, as the water molecules absorb the energy, it increases the temperature of the food.
Name a uses for Infrared EM waves?
- Infrared Cameras - to check for heat loss
- Electrical heaters - when emitted the infrared waves
energy is easily absorbed by other objects,
increasing there temp
Name some uses of visible light?
Fibre Optics
What are optical fibres?
Thin glass or plastic fibre that can carry data over long distances. They work due to reflection as visible light is reflected along the fibre.
Why is visible light used in Fibre optics?
Due to visible lights short wavelength, it can carry lots of information.
Name some uses for UV waves?
1) Energy efficient lightbulbs
2) Tanning Salons
3) Fluorescent lights
Why are UV waves used in energy efficient lightbulbs?
Due to its short wavelengths, it carries more energy than visible light, this energy is then absorbed by the interior surface of the bulb and turned into visible light.
This requires much less energy than a normal light bulb.
What are both X-Rays and Gamma Rays used for?
Medical imaging
- X Rays used to visualise broken bones
- Gamma Rays can be used to detect cancer - as they
are very penetrating and can pass through the body
tissue
Why are X-Rays used to see bones?
X-Rays are very penetrative (able to make it through human skin and bones) and are then absorbed by the bones so that they can be seen.
What are the dangers of Low-Frequency waves?
None, as they don’t transfer much energy and so mostly pass through soft tissue without being absorbed.
What is the danger of UV radiation?
Damages surface cells, which can lead to sunburn and further develop into an increased risk of skin cancer
What is the danger of X-Rays and Gamma rays?
They are a type of ionising radiation that can cause gene mutation or cell destruction, and cancer.
What is done before any of the high-frequency types of radiation are used in medical injuries?
The risks and benefits and measured up.
What are radiation doses measured in?
Sieverts (Sv) - is a measure of the risk of harm from the body being exposed to radiation (measured normally in millisieverts 1000 mSv = 1 Sv)
What does the radiation dose risk depend on?
The total amount of radiation absorbed AND how harmful it is.
Where is Infrared radiation emitted from?
The surface of an object (the hotter the object the more IR radiation is given at a time)
How do some colours affect the rate of absorption of IR radiation?
Some colours e.g black are better at absorbing and emitting radiation than white.
Or Matte surfaces are better at absorbing and emitting radiation than a shiny one
Objects at a constant temperature are emitting infrared radiation….?
At the same rate as they are absorbing it
What happens to an object that is hotter than its surroundings?
It is emitting more IR radiation than it absorbs as it cools down.
What happens to an object that is cooler than its surroundings?
They absorb more IR radiation than it emits as it warms up.
