An EM wave is caused by an energy source, such as something as big as a supernova or something as small as an electron changing in speed. I would say the change in the energy level of the energetic particle that causes the wave determines the frequency of the wave.
+++
Whilst you may be right about the quantum physics, the frequency of the wave is that of the energy source, be it in a star or a radio transmitter, driving it.
Frequency determines this.
Radio Waves.
Geomagnetic waves are thought to be the lowest frequency (and, therefore, the longest wavelength) electromagnetic waves in the universe. They are generated by movements in planetary structures that modulate a planet's magnetic field to create the wave. Certainly lower frequency electromagnetic waves could be generated, but they would be artificial. A link is provided for some useful information.
Yellow light has the lowest frequency among the electromagnetic waves listed. The frequency of electromagnetic waves increases from radio waves to gamma rays, with yellow light falling in the visible light spectrum.
Electromagnetic waves vary in frequency, wavelength, and energy. These properties determine the type of electromagnetic wave, such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each type of electromagnetic wave has unique characteristics and uses.
Frequency determines this.
Frequency determines this.
The plasma frequency is important in the study of electromagnetic waves because it determines the frequency at which a plasma can oscillate. This frequency affects how electromagnetic waves interact with plasmas, which is crucial in various fields such as astrophysics, plasma physics, and communication technology.
The highest frequency electromagnetic waves are gamma rays.
Light energy travels in the form of electromagnetic waves. These waves are composed of oscillating electric and magnetic fields that propagate through space. The wavelength of light determines its color, and the frequency determines its energy.
The wavelength of electromagnetic waves decreases as the frequency increases.
The relationship between frequency and energy in electromagnetic waves is that higher frequency waves have higher energy. This means that as the frequency of an electromagnetic wave increases, so does its energy.
The frequency range for electromagnetic waves is from about 3 Hz (hertz) to 300 EHz (exahertz).
There is no upper limit to how much energy (and frequency) an electromagnetic wave can have. The highest frequency waves are called gamma radiation.There is no upper limit to how much energy (and frequency) an electromagnetic wave can have. The highest frequency waves are called gamma radiation.There is no upper limit to how much energy (and frequency) an electromagnetic wave can have. The highest frequency waves are called gamma radiation.There is no upper limit to how much energy (and frequency) an electromagnetic wave can have. The highest frequency waves are called gamma radiation.
Radio waves are electromagnetic waves occurring on the radio frequency portion of the electromagnetic spectrum.
The energy of electromagnetic waves is carried by photons, which are particles of light. The energy of electromagnetic waves increases as the frequency of the waves increases.
Radio waves have the lowest frequency among the electromagnetic waves. They have frequencies ranging from 3 kHz to 300 GHz.