14.2 Electromagnetic Waves Flashcards
How are electromagnetic waves created?
By accelerating charged particles
What do these waves have?
Perpendicular to each other electric and magnetic fields with the same frequency as the source
Do electromagnetic waves require a medium?
No, they can travel in a vacuum
What is their speed in a vacuum?
3x10^8 ms^-1 (the speed of light)
Can an em exist without one of the fields?
No
What is another way of creating electromagnetic waves
By making electrons fall back to original shell after they become excited. EM waves would then be released as photons.
Wavelength range of radio waves? 1 use
10^-3 - 10^5 radio signals (range of frequencies)
Wavelength range of microwaves?
10^-4 - 10^-1
heating food by resonance
satellite communications
Wavelength range of infrared
10^-7 - 10^-3
emitted by warm bodies
heating,cooking
Wavelength range of visible light?
4-7 x 10^-7
creates a visual image in the brain
photosynthesis
Wavelength range of ultraviolet?
10^-10 - 10^-8
fluoresecent lamps and detecting forged banknotes
photoelectric effect
production of vitamin D in the skin resulting in tanning
Wavelength range of x rays?
10^-14 - 10^-10
What is the range of gamma?
10^-16 - 10^-11
detecting tumors
What type of a wave are EM waves?
transverse waves
Do EM waves carry energy (are they progressive)?
Yes
