chapter 8- electromagnetic waves Flashcards
electromagnetic spectrum
in order from longest wavelength to shortest wavelength:
-Radio
-microwaves
-inferred
-visible light
-ultraviolet radiation
- X- rays and gamma rays
infrared radiation
-the hotter the object, the more infrared radiation it emits
- it is absorbed by the skin–> it can burn or kill the skin cells, since it heats up the cells
infrared devices
-optical fibres
-remote control handsets
-infrared scanners
-infrared cameras
microwaves
-used for communications
e.g. satellite TV, since the microwaves can pass through the earths atmosphere and reach satellites above earth
-also used to carry mobile phones signals
radio waves
used for radio and TV broadcasting, radio communications and mobile phone calls
the shorter the wavelength
-the more info they carry
-the shorter the range –> increasing absorption by the atmosphere
-the less they spread out –> they diffract less
optical fibres
very thin fibres, used to transmit signals by light and infrared radiation
- carry more info than radio and microwave communications
- more secure than radio and microwaves communications
ultraviolet radiation
-smaller than visible lights wavelength
-carries more energy
X-rays and gamma rays similarities
-can damage living tissue when they pass through it
-carry much more energy per second –> short wavelength
X-rays and gamma rays differences
-gamma rays are produced by radioactive substances when unstable nuclei releases energy
-gamma rays have a shorter wavelength
-X-rays are produced in an X-ray tube
using gamma radiation
-killing harmful bacteria in food
-sterilising surgical instruments
-killing cancer cells
X- rays in medicine
-make images and CT scans
- destroy tumors at or near the body surface
