zlacker

Low, medium, and high-frequency radio waves (below 30MHz, wavelengths longer than 10 meters) are a form of EM radiation. Which means that an antenna is 'transmitting' low-energy, long-wavelength photons. (Which gets us into the whole wavicle question.) But the signal from a radio station appears to be continuous.

So: how to picture this? Is the signal made of discrete 'photons' overlapping, or combined somehow? Or is it that the 'wave-like' aspect of these photons is so predominant at these frequencies? (I've grappled with this one for a long time.)

>>8bitsr+(OP)
A radio station in the 1MHz range is transmitting in the 10s of kW range. The energy of a single photon is tremendously small. So if you divide out the large transmitting power by the energy of a single photon, you'll see that an unimaginable number of photons is being released, giving the impression of a continuous process.

More detail:

Say you have an AM station that transmits at frequency f = 650kHz and uses power P = 50kW.

The equation for a photon's energy is E = hf, where E is the energy, h is Planck's constant and f is the frequency. Here h = 6.6310^(-34) Js and f = 6.510^5 Hz. Thus the photon's energy is E = 4.3110^(-28) J. This is very tiny number.

The number of photons per second is n = P/E = 1.1610^32.

Let's try to visualize this. Avogadro's number is 6.022*10^23 for each mol of something, so if we divide it out from n, we see that there are almost 200 million mol of photons being released every second!

Water is 18g/mol, which takes up about 16 cm^3. 200 million moles of water is about a million gallons. If a photon was like a water molecule, a "water AM station" would be releasing about a million gallons of water per second.

>>vlasev+t6
Thanks, Vlasev, helpful ... easy to scale down to my hometown's measly 2,000 gallon AM station. I guess I'll need to go back to the radio physics math and puzzle it out more (directional arrays, groundwaves, and the like.) The idea of a photon with such a miniscule energy yet a wavelength of a thousand meters is a tad non-intuitive to me.