Chapter 5 - EM Waves Flashcards
What is the EM waves our eyes detect?
Visible
Name the 7 parts of the EM spectrum in order from longest to shortest waves
Radio waves, microwaves, infra red rays, visible, ultraviolet waves, X rays, gamma rays
Which wave has the highest energy and the highest frequency?
Gamma rays
Which wave has the lowest frequency and the lowest energy ?
Radio waves
What size does visible light rays range? What are the colours of each end?
390 nm, violet
698nm, red
What are the uses of infra red?
Cooking, remotes, fibre optics, communication
What are the uses of gamma?
Sterilising food and equipment, gamma knifes / radiotherapy
What are radio waves used for ?
Communicating
What are microwaves used for?
Communicating and cooking
What are x rays used for?
Security scans, imaging hard tissue
How large are radio waves?
100km to 1m
How large are microwaves?
1m to 1mm
How large are infra red rays?
1mm to 698 nm
Can EM waves travel through a vacuum? How do we know this?
Yes, we can feel the UV rays from the sun and see visible light of stars
What rays are absorbed by the atmosphere?
Gamma , x rays, some UV, some Radio and some microwaves
How large are gamma rays?
100 pm , picometres, 1 trillionth of a metre
Which wave is getting trapped in our atmosphere more? What is causing this?
Infra red, the increase of greenhouse gases is causing this and this is causing the Earth to heat up
Which is the least dangerous out of all the EM waves? Which is the most dangerous?
Radio is the least dangerous, gamma is the most
How is UV rays dangerous?
It can cause skin cancers by making mutations in the cells
How’s gamma dangerous?
It’s radioactive, can kill cells or cause very bad mutations in them
How is visible light dangerous?
It can blind you if you have to much at once, like looking into the sun or a layer
How are x rays dangerous?
Damages living tissue, general cancer causer so there is a cap on x rays you can have a year
How is infra red dangerous?
Can cause skin burns, heating of body tissues , break up of cells
How are microwaves dangerous?
They can heat from the inside, mobile phone signals could cause very dangerous brain cancers (not certain yet)
What do filters do to visible light?
Only allow a certain colour through, or whatever makes up that colour
What colour would green appear under a yellow filter? What about blue under a yellow filter?
Green would still appear green through yellow filter because yellow is made up of 2 out of 3 primary colours red and green so the yellow filter is still letting green through. Blue would appear black under a yellow filter because yellow isn’t letting any blue through so the object doesn’t reflect any colour
What are the 3 primary colours (in PHYSICS not art, hint: think about the eye)?
The colours our eyes detect which make up all the other colours our eyes detect, red, green and blue
Under a blue filter what does a white object appear as? Is this the same for other colours? Why?
It appears blue, under any colour filter white appears the same colour as that filter. This is because white absorbs and reflects all colours so if it is only absorbing one colour, in this case blue, then it is only able to reflect that colour too.
