P13 (Electromagnetic Waves) Flashcards
Electromagnetic Waves
- transverse waves transfers energy from a source go the absorber
- same speed through air and vacuum
Order if Em spectrum
- Radio waves
- microwaves
- infrared
- visible light
- Ultra Violet
- X rays
- gamma rays
As waves go from radio to gamma…
- increases frequency
- decreases wavelength
Altering current to produce radio waves
- in transmitter the electrons oscillates and produces Em waves
- emits radio waves and transmits energy
- receiver absorbs and causes electrons to oscillate
Use of Radio Waves
- communication (radio and tv)
- waves diffract around the curved surface for signal to reach different places in the world
2 Uses of microwaves
- microwaves sent to signal and transferred back to earth
- can travel through watery atmosphere for Tv and phones
- in microwaves to heat food as it penetrates the food to heat up the water molecule
3 uses of Infrared Radiation
- infrared cameras detect temperature so brighter light on screens= higher temperatures
- heat up food when absorbed
- electrical heaters and objects absorb it to heat room
Fibre Optics
- thin glass or plastic fibres carry data
- reflection of visible light along the glass bouncing
2 Uses of Ultraviolet Radiation
- from the sun and tanning salons for a tan
- used for lights which are energy efficient and last long
How X-rays and Gamma rays are used in medicine
- pass through body but can’t penetrate bone so it produces images of the bones
- gamma rays kill cancer cells, as they’re focused on the specific area
- used for medical tracers to detect problems as they can see through body
3 ways Em waves harm people
- UV can cause sunburn and skin cancer
- UV causes blindness
- X Rays and Gamma rays produce ionising radiation that knock off the electrons causing mutation in cells (in genes)
Radiation dose
- risk of harm to he body when being exposed to radiation
- depends on how much and what radiation
Visible Light
- ROYGBIV
- primary colours and red, green and blue and you can’t mix
- mix all creates white light
Absorbing in white and black objects
- white light reflects all equally
- black light absorbs all light
Colour filters
Filter out different wavelengths of light so that only certain colours are absorbed
Black Bodies
- perfect black body is an object that absorbs all radiation (none reflected or transmitted)
Effect of shorter wavelength on intensity
shorter wavelengths increase intensity more rapidly than longer
wave lengths as it increases temp, causing the peak wavelength to decrease
How radiation effects temperature
- in day earth absorbs it during the day to increase local temps
- at night less absorption that being emitted so decrease temp
- earth keeps at constant temp apart from global warming
