Tilted Forum Project Discussion Community - View Single Post

fuzzybottom · 10-28-2005, 11:45 AM

ive been reading through all of this and its made me wonder about a few things

to clarify, is the speed of light, c, the speed of all electromagnetic waves, or just the visible spectrum?

do electromagnetic waves interfere with eachother like soundwaves do? like, if a wave of blue light and a wave of red light crossed paths would they combine to a purple light, or is that combination done by the eye, after registerting red and blue light separately but simultaneously?

EM waves have energy and momentum right? but momentum is p=mv. but EM waves dont have mass, and i guess E=mc² covers for that, so their momentum would be something like p=(E/c²)v where v = c, giving E/c, and since E = hc/L, it could be represented as p=h/L, or p=hf, or am i talking out of my ass. (L being lamda)

my main reason for the last question is, if they have momentum, in any reflection off a surface, conservation of momentum would have to be applied, and as such, the momentum of the wave would be affected, but since it doesnt have mass, its change would be exhibited by a change of energy, essentially a change of frequency, which would change its appearance if it happened to be a color, though only to some incredibly small degree.

and if anyone can explain why the c would be the same regardless of observers relative speeds, id love them forever =/

edit:
sorry, another question.
i know light only travels at c in a vacuum, but if it is released from a medium in which it moves slower into a vacuum, does it accelerate to c again, or maintain its lower velocity?

10-28-2005, 11:45 AM	#9 (permalink)
fuzzybottom Upright	ive been reading through all of this and its made me wonder about a few things to clarify, is the speed of light, c, the speed of all electromagnetic waves, or just the visible spectrum? do electromagnetic waves interfere with eachother like soundwaves do? like, if a wave of blue light and a wave of red light crossed paths would they combine to a purple light, or is that combination done by the eye, after registerting red and blue light separately but simultaneously? EM waves have energy and momentum right? but momentum is p=mv. but EM waves dont have mass, and i guess E=mc² covers for that, so their momentum would be something like p=(E/c²)v where v = c, giving E/c, and since E = hc/L, it could be represented as p=h/L, or p=hf, or am i talking out of my ass. (L being lamda) my main reason for the last question is, if they have momentum, in any reflection off a surface, conservation of momentum would have to be applied, and as such, the momentum of the wave would be affected, but since it doesnt have mass, its change would be exhibited by a change of energy, essentially a change of frequency, which would change its appearance if it happened to be a color, though only to some incredibly small degree. and if anyone can explain why the c would be the same regardless of observers relative speeds, id love them forever =/ edit: sorry, another question. i know light only travels at c in a vacuum, but if it is released from a medium in which it moves slower into a vacuum, does it accelerate to c again, or maintain its lower velocity? Last edited by fuzzybottom; 10-28-2005 at 11:48 AM..