does an electromagnetic wave of frequency less than 1hz exist?

Answer 1

Yes, they do. In fact most EM waves of interest are less than 1 hz.

Answer 2

By definition this is a "Radio" wave. which is not commonly used for transmitting information at low frequencies. The navy has used ELF (Exrtemely Low Frequency) waves to transmit through the Earth's crust.
But technically the phenonenon of elecrtomagnetic wave propagation is not restricted to high frequencies. Imagine a plate being suddenly charged. In practice when you do this it shoots up in charge then down so it kind of rings at some frequency.
Hertz studied the disturbances caused by lightning and found there were many Frequencies.
Here is something to think about. The electric power grid of the entire US is constantly radiating 60HZ out into space. How much energy is being lost there? Where does it go?

Answer 3

1 Hz Frequency

Answer 4

I'm not sure why you'd think that 1 Hz is any kind of limit.

1 Hz means one cycle per second. We (people) made up the second (probably from the heartbeat, but who knows). There is no reason you couldn't have a frequency of, say 1/2 Hz.

Answer 5

Theoretically yes, but such a frequency would have a wavelength of something like 186-thousand miles.