system
Given the following post, respond as if you're commenting on Reddit:
human
What is the lowest radio frequency?

Is there a minimum frequency for electromagnetic radiation? Below a certain frequency, would the energy of each photon be below some quantum limit?

Do AC power lines emit photons of 60Hz (50Hz) radiation? Would there be any effects one could test for to exhibit the particle nature of such low frequency radiation?
gpt
There is no lower limit to radio frequency.  All radiation has a quanta of hv, where v is the frequency and h is planck's constant.

Below a certain energy, it gets hard to detect individual photons, so then radiation is detected with antennas. Antennas need to be a good fraction of the wavelength of radiation.  Thus the size of the antenna places technological limits on the lowest practical radio frequency.

Very low frequency radiation (<100 Hz) has some applications.  The US Navy used to maintain a facility to transmit signals on 76 Hz to submarines.  These signals were the only one capable of penetrating seawater to submarine depth.  The bandwidth on these signals was very small.  They could only send a few characters per minute and the antennas were 30 miles long but hugely inefficient.