P12 Electromagnetic Waves Flashcards
How are EM waves made?
Oscillating electric and magnetic field
How are alternate currents made?
What do they produce?
Made up of oscillating charges which produce osillating electric and magnetic fields aka electrmagjetic waves
What does the frequecncy of a wave equal to?
The alternating current.
How do you produce radio waves?
Ossilations in an electrical circut.
What are radio waves used for?
Communication
How long is the wavelength of a radio wave?
1-10km
What is diffraction?
What waves diffract?
The prosses of which a wave bends around an object eg a hill. Therefore radio waves can be recived even when you cannot conect the transmitter and reciever with a straight unbrocken line.
Waves with longer wavelengths difracts better.
How does the wavelength of a wave affect it’s ability to go through the ionesphere
The longer the wavelength the more chance it has of passing through the ionesphere. Waves with a wavlength of about 1km-10km can pass through it but waves with a wavelength of about 10m-100m can’t and will reflect off of it.
What waves are used for TV and FR radios?
Radio waves. They use shorter wavelengths so they do not refract well.
What is the order of the EM Spectrum
Radio Waves Micro Waves Infrared Radiation Visable Light (In order of Red Orange Yellow Green Blue Indigo Violet) UltraViolet X-rays Gama-Rays
Which wave has the shortest wavelength?
Gamma-Rays
Which wave has the longest wavelength?
Radio-Waves
Which waves have the highest frequency?
Gamma-Rays
What wave has the lowest frequency
Radio Waves
Give 2 uses for Radio waves
Radio signals
Tv signals
Walky talkys
Give 2 uses of Micro Waves
Cooking food
Radar
MOBILE phone
Give 2 uses of infrared radiation
Thermal imaging camaras
Night vision
Cooking (not with a microwave)
Give 2 uses of Visable light
Sight
Cammara
Give 2 uses of UltraViolet
Detective forgery money
To clean water
Give 2 uses of X-rays
Medical diagnosis
Security
Give 2 uses of Gamma-rays
Medical diagnosis
Sterilise medical equipment
Kill cancerous cells
Give 2 dangers of Radio waves
There are none
Give 2 dangers of Microwaves
Internal heating
Give 2 dangers of InfraRed Radiation
Internal heating leading to burns
Eye damage
Give 2 dangers of visable light
Eye damage
Give 2 dangers of UltraViolet
Sun burn
Skin cancer
Give 2 dangers of X-Rays
Radiation which leads to cancer
Damage of the skin
Give 2 dangers of Gamma-Rays
Radiation leading to cancer
Skin or blood diseases
Kills cells
What is an optical fibre?
Thin glass of plastic fibres that can carry data over long distances as pulses of visable light know as total internal reflexion
They are very quick
How fast do all electromagnetic waves travel in a vacume
3x10^8
How do you calcuate wave speed?
Ws = F X Wl
Wave Speed (m/s) = Frequency (Hz) X Wave Length (M)
What are 3 things all EM waves have in common?
They travel at 3X10^8 m/s in a vacume
They can all travel through a vacume
They are all transverce waves
What are carrier waves used for?
TV signals and satalite communication
1Sv = ?mSv
1000mSv
