hello guys,
i need to know please how can a radio communication be made between a station on earth and a station in space nevertheless the physical world around it is different in space than on earth ?
Radio waves are electromagnetic waves and travel through vacuum as well as air (and many other materials). The "connection" follows the same principles in outer space as it does on Earth.
Basically you can't do this without a license as we have gone through many times before.
Get yourself a ham license and you can build a transmitter to contact space.
These people run ham satellites:-
Most radio frequencies above 30MHz get into space, lower ones can bounce off the ionosphere back to Earth before leaking into space.
Grumpy_Mike:
Basically you can't do this without a license as we have gone through many times before.Get yourself a ham license and you can build a transmitter to contact space.
These people run ham satellites:-
http://amsat-uk.org/
AMSAT - WikipediaMost radio frequencies above 30MHz get into space, lower ones can bounce off the ionosphere back to Earth before leaking into space.
no i wasn't asking for any project, it's just information that i needed to know
i will get it later of course when i really have an idea of what i am doing and i will be able to design, i am studying now the handbook for ham radio it's really great !
jremington:
Radio waves are electromagnetic waves and travel through vacuum as well as air (and many other materials). The "connection" follows the same principles in outer space as it does on Earth.
but there is no air in space, like on earth so how does that work ! or it is still a mystery i guess which haven't been solved yet
or it is still a mystery i guess which haven't been solved yet
The mystery was solved in the 1800's when Maxwell formulated the mathematical equations that governed electromagnetic fields. Maxwell's equations - Wikipedia
The theory of electromagnetism is one of the best, most accurate and most completely understood theories in all of physics.
Why should they need air? As jremington said, EM waves can travel through a vacuum. If that wasn't the case, it would be dark since the light from the sun (also EM) wouldn't get to us.
You're thinking as if everything worked like sound, which doesn't work in a vacuum, becasue of the different make up of a sound wave; it's essentially a movement of the particles of the medium. You're in good company though, since this was a vexing question to everyone, years ago.
Quick Google revealed loads of articles like this: Cornell Center for Materials Research - Ask a Scientist
JimboZA:
Why should they need air? As jremington said, EM waves can travel through a vacuum. If that wasn't the case, it would be dark since the light from the sun (also EM) wouldn't get to us.You're thinking as if everything worked like sound, which doesn't work in a vacuum, becasue of the different make up of a sound wave; it's essentially a movement of the particles of the medium. You're in good company though, since this was a vexing question to everyone, years ago.
Quick Google revealed loads of articles like this: Cornell Center for Materials Research - Ask a Scientist
yes your right i was thinking like the sound
jremington:
The mystery was solved in the 1800's when Maxwell formulated the mathematical equations that governed electromagnetic fields. Maxwell's equations - Wikipedia
The theory of electromagnetism is one of the best, most accurate and most completely understood theories in all of physics.
what i meant by mystery is that how in fact an electromagnetic wave travels, it is actually like magic thing
if there is vacuum then it's nature is something unusual
The theory of electromagnetism is one of the best, most accurate and most completely understood theories in all of physics.
There is no vacuum.. The "empty space" is full of matter and energy. I've been just waiting on someone coming with a new theory on how the emag waves actually travel.. (and what the electromagnetism actually is like..) 
firashelou:
jremington:
The mystery was solved in the 1800's when Maxwell formulated the mathematical equations that governed electromagnetic fields. Maxwell's equations - Wikipedia
The theory of electromagnetism is one of the best, most accurate and most completely understood theories in all of physics.what i meant by mystery is that how in fact an electromagnetic wave travels, it is actually like magic thing
if there is vacuum then it's nature is something unusual
Many scientists in the 1800's got this wrong too, so don't feel bad.
There was a famous experiment called the Michelson-Morley experiment that
demonstrated that em-waves do not travel through a medium (well that was the
least crazy explanation).
Maxwell's equations show that a changing electric field generates magnetic field,
and changing magnetic field generates electric field. One form of solution to the
equations is a wave travelling at the speed of light. The speed of light and
the permeability and permittivity of a vacuum are directly related.
Its only with special relativity and quantum mechanics in the 20th century that
the true significance of this became known (Maxwells equations are an emergent
property of quantum electro-dynamics, which is the theory of electron and photon
interactions.)
what i meant by mystery is that how in fact an electromagnetic wave travels, it is actually like magic thing
if there is vacuum then it's nature is something unusual
Not magical just a natural consequence of physics.
Think of it like this:-
An electric field is produced from zero to some maximum, this causes a magnetic field to be produced in front of the electric field. When the electric field stops increasing and starts declining the magnetic field starts to collapse as well. Now the clever bit is that the collapsing magnetic field causes a rising electric field just in front of it, which in turn forms another magnetic field in front of that. This series of collapsing and generated fields propagates outwards and is electromagnetic radiation, or radio / light / x-ray waves.
This occurs in a vacuum at the maximum speed. Through other media like air, glass or wire it slows down and travels slower than light in a vacuum.
Electromagnetism makes a lot more sense than the moronic explanations of how gravity works.
yes but the magnetic field is not explained i mean no one knows what really is it ! it's simply still magic !
it's not like the air or like the electricity, it simply can't be explained i don't think it's material !
firashelou:
yes but the magnetic field is not explained i mean no one knows what really is it ! it's simply still magic !
it's not like the air or like the electricity, it simply can't be explained i don't think it's material !
What sort of explanation would you like for a magnetic field? We know all about it how to calculate it and how it acts. We can write the equations that fully describe it. There is no magic about it. It is just another aspect of an electric field. No it is not material it is a force.
Grumpy_Mike, that is the best and clearest explanation of EM waves that I have ever seen. Been around a while, too.
There's also wave/particle duality. You can think of your radio beam as a modulated stream of particles (photons) traveling through space, or air, or whatever. That way, you don't have the whole "how can you have waves if there's no medium for the waves to be IN?" question.
Grumpy_Mike:
What sort of explanation would you like for a magnetic field? We know all about it how to calculate it and how it acts. We can write the equations that fully describe it. There is no magic about it. It is just another aspect of an electric field. No it is not material it is a force.
aha ok i guess it's better now thanks Grumpy Mike 
westfw:
There's also wave/particle duality. You can think of your radio beam as a modulated stream of particles (photons) traveling through space, or air, or whatever. That way, you don't have the whole "how can you have waves if there's no medium for the waves to be IN?" question.
i can go with the photons choice 
@firashelou
You said EM is like magic, but isn't all you see like magic?
All formulas of physics is just our way to make a model of what our sensors see/hear/etc and to predict behaviour.
These models have been refined and improved very much,
You should read Bill Brysons book : - http://www.amazon.com/Short-History-Nearly-Everything/dp/0767908171 -
explains a lot (and triggers even more questions:)