How is it that radio waves travel faster than sound waves? I was always taught that antennas work like tuning forks, ie if you have 2 of the same tuning forks in a room and tap on one of them, the other one in the room will begin to resonate and make noise too. But clearly radio waves are not sound waves? Is there a way that one could ever hear radio waves?
Part of the spectrum that includes visible light. No prizes for guessing what speed they travel at.. IIRC, it's Gamma rays, X-rays, UV, visible, IR, microwaves, then radio waves. And look, graffitti on the wall! - "Heisenberg may have been here"
That's the electromagnetic spectrum nailed (short wavelength -> long) (high frequency -> low frequency therefore high energy -> low energy[1]). And yes, they all travel at c (3E8 ms-1) as the gauge boson of electromagnetism is the photon. [1] X-rays can have higher E than gamma rays, but gamma and X rays are basically the same thing, but gamma rays MUST be emitted from the nucleus.
Ok, right - antennas! I'm sorry if I seem patronising but I don't know how much you know , and if I get something wrong please can someone correct me Radio waves are basically particles called photons, as is every wave in the electromagnetic spectrum. They seem to have wavelike qualities because of quantum motion, but that's an awfully complicated topic that we don't need to go into. Now when we put energy into an atom we can get it to emit a photon. Think of a light bulb - when energy is put into it as electrical current it emits photons which have a wavelength that are in the visible spectrum so we see them. We can do the same with an antenna - only the photons are emitted have a wavelength in the radio spectrum and the extra energy comes from pumping a current up and down the antenna. The rate at which the current is pumped up and down could directly be linked to the rate at which the tuning fork vibrates in the image you have. The same process works in opposite at the receiver, photons hitting the antenna give the antenna extra energy which creates an electrical currents pumping up and down the antenna.
Ok, I just got this bizarre idea into my head. What if the ozone layer were built of other materials (Nothing else taken into consideration. This is only hypothetical) which made it let trough only, say x-rays, but not light. Do you all think the human body would evolve to have eyes that can see using x-rays and not light? That would be really cool, actually. "Hey, you have the sexiest femur I have seen in years!"
Umm, no. There's plenty of IR spectra around, but human eyes arent' sensitive to those wavelengths now, are they? Not to mention that the x-rays would cook the planet and everything on it. I think. Your hypothesis is quite interesting, though.
so light is somehow emitted from the antennas? So radio waves should have no problem going through glass right? And to think that I always opened my window every time when I stole my neighbor's wifi... But then how does this "light" go around something solid? If I put an antenna behind a brick wall I can still get a signal....
Photons, yes. But they ain't in the light section of the spectrum. Wave particle duality. Photons refract (quantum phasors trying all paths and whatnot...).
Photons in the radio wave spectrum have less energy than photons of visible light, so do not have enough energy to pass through the glass. Visible light does this too, just to a lesser amount due to shorter wavelength/faster phasor rotation.
Of course. The "visible spectrum" is basically what the sun emits most of. Plenty being about less than 10% of visible light IIRC
It depends where the signal is coming from, and what frequency it is at. Radio wave propagation is not simple, and people always assume that a signal leaves the tx antenna and arrives at the rx antenna via the shortest possible route... ie, line of sight. Not so. Short range, low power signals such as a wi-fi connection will usually be line of sight, and while they will pass through a building, it will be severely attenuated by the time it arrives. Buildings and other large objects will gradually reflect, diffuse, or absorb the signal as it passes though. Higher frequency signals will suffer more than low frequency signals. High frequency signals can simply reflected around corners also, giving the impression it's passing through a building that appears to be in the way, when in fact it's bouncing off an adjacent building instead. Long distance communication on HF (short wave) is not line of sight, and is usually received via what's called ionospheric propagation. This means the radio waves are refracted (bent) by charged particles in the ionosphere... rather like a lens refracting light, and bent back down to earth. This can happen several times with the signal bouncing back up, and down again. The distance achieved depends on the frequency, number of active sunspots at the time, angle of transmission, and which layer of the atmosphere is refracting the signal. Ironically there's a layer of the ionosphere which can block long distance propagation at lower frequencies, and this is why you can only usually receive foreign radio stations on AM at night... not the day, because the solar radiation that charged the layer during the day is no longer present. It's a very complicated subject.. and fascinating... You can even use meteor showers to propagate a signal... or even use the moon as a reflector. All good stuff Unfortunately we're at a sunspot minimum at the moment.. so no play time for me It goes in a 11 year cycle too, so there's lots of down time.
