longest wavelength EM wave
radio waves
highest frequency EM wave
gamma rays
how fast are all EM waves
3x 10 (power of 8)
how to produce and detect radio waves
- oscillating p.d across wire produces a changing electric and magnetic field
- emits radio waves
- detected by an aerial, fields meet together
EM Waves used for communication
- microwaves (phone , satellites and wifi systems)
- radio waves (radio stations)
- infrared waves (remote controls )
- visible light ( flashing morse code , ships)
infrared uses
communication in remotes
cooking food, by transferring energy to a thermal store
medical imaging
ultraviolet light uses
- produce vitamin D
- detect bodily fluid for forensic scientists
what EM waves damage cells?
ultra violet - kills bacteria and sterilises water (can damage DNA, IF EXPOSED TO EYES develop cataracts)
X-rays- kill skin cancer and other cancer cells (cause cancer)
gamma rays- kill cancer cells and kill bacteria (and other bodily cells)
how infrared waves are used for medical imaging
- thermal imaging camera (produced THERMOGRAM)
- pixels in à CCD absorb infrared to produce an image
- skin will emit more radiation if there is an injury or infection
- also used to show flow blood vessels
how X-rays are used in imaging
-bones absorb x-rays , not muscle or soft tissue
- CCD used to detect x-rays
- colours show difference in intensity due to densities of bones
How gamma rays used for imaging
- used as tracers
- patient injected with radioactive substance that emits gamma rays (tracer)
- kidney absorbs tracer
- tracers also used to find leaks in underground pipes
