These notes contain summary notes on the topic Electromagnetic Waves in physics. They helped me achieve distinction overall and are easy to understand.
EM Spectrum = is a continuous range of wavelengths
= range of all types of EM radiation
= the uses and dangers differ depending on their wavelength and frequency
The spectrum is made up of EM waves
EM Waves:
EM Waves/Electromagnetic Waves = are transverse waves that are created as a result of
vibrations between an electric field and a magnetic field
Below is a table of all the waves
Energy Frequency Wavelength Radiation type Typical use
Lowest Lowest Longest Radio waves Television signals
Microwaves Cooking, Mobile phones
Infrared Optical Fibre Communication
Visible light Seeing
Ultraviolet Detecting Forged Bank Notes
X-rays Medical Images of Bones
Highest Highest Shortest Gamma radiation Killing Cancer Cells
Radio Waves
Are used for communication (e.g. broadcasting TV, radio, communications and satellite
transmissions)
They’re easily transmitted through the air
How do they work?
They are produced by oscillations in electrical circuits.
When the waves have been absorbed by a conductor, they create an alternating current.
This current has the same frequency as the radio wave.
Info is coded into the wave before transmission/transfer.
This is info can then be decoded when received.
TV and radio systems use this method to broadcast info.
Positives = don’t damage the body if absorbed.
= can be reflected to change their direction (which makes them better suited for signals and
communications)
Negatives = it has low frequency (can’t send a lot of info/data at once)
Microwaves Waves
Are used for cooking food, communications and satellite communications
How do they work?
Microwaves with high frequencies are easily absorbed by molecules found in food.
The molecules internal energy increase when absorbed by the microwaves.
This causes heating.
Positives = can pass easily through atmospheres (so they can pass between stations on earth and
satellites in orbit)
Negatives = if exposed to high frequency microwaves you can get a painful burn
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