Topic 2 - The Elcteomagnetic Spectrum Flashcards
What is the rule for frequency and wavelength on the EM Spectrum
Increasing the frequency and decreasing the wavelength as you go from radio waves to gamma rays
What are the seven parts to the electromagnetic spectrum?
Radio waves Microwaves Infrared Visible light Ultra violet X rays Gamma rays
What did Herschel discover in 1800
Infrared radiation while experimenting with sunlight and a prism
He used a thermometer to measure each colours temp.
It increased from violet to red
No visible light past red=Infrared
What did Ritter discover in 1801?
Ultraviolet radiation, an invisible form of light that exists on the other side
How are Microwaves harmful?
Heat body cells
Mobile phones use MWaves
Increasing use in mobile phones more of a risk
How is Infrared harmful ?
Heating effect
Higher frequency = more energy
Causes skin burns
The surface molecules of any substance vibrate = heat
How is Ultraviolet harmful?
More energy higher frequency
Causes skinburn which is when skin cells absorbed too much UV
Can cause cell mutation skin cancer and eye damage
How is Gamma rays harmful ?
Very high frequency , very high energy, more than UV
Penetrates further into the body
Causes cell mutation / destruction and tissue damage and cancer
What are different points about radio waves = communication
Long wave radio (1-10km)=Bend around curved of the earth
Short Wave Radio(10-100m)=Long distance only if reflected by ionosphere
V Short Radio(10cm-10m)=TV and FM Radio transmissions in sight of transmitter
How are microwaves used as satellite communication and mobile phones?
Time delays = transmitted into space and back to earth
Mobile Phones= phone to transmitter as microwaves
How do microwave oven use a different microwave length from satalites?
Communications pass through watery atmosphere
Heat energy is then conducted or converted to other parts of the food
What is infrared radiation?
Used to monitor temperature
Heat loss through houses can be detected
Used as night vision equipment to detect the heat coming off bodies. Hotter the object the brighter.
How do Optical fibres use infrared radiation to transmit data?
Can carry data over long distances as infrared as repeated reflections.
It can be used for cooking eg Grills
Remote controls eg transfer info
Transmit info between mobile phones or computers over only short distances
Sensors in security systems eg Burglar alarms
What is visible light?
Only see objects because they give or reflect light
Light entering your eyes gets refracted
Messages sent to your brains via optic nerve
What us UV radiation for ?
Detecting forged bank notes
Fluorescence = ultraviolet is absorbed by it
Bank notes have fluorescent markings to show wether the notes are real or not
