The energy of a photon is directly proportional to its.....

I think it may be frequency.
Is that correct?

yes.

Energy = h(a constant) x frequency.
Therefore, the higher the frequency, the higher the energy. The lower the frequency the lower the energy. It's inversely proportional to the wavelength.
E = hc/wavelength where both h and c are constants. Therefore, the short wavelengths (the higher frequency) are the most energetic.

Yes, that is correct. The energy of a photon is directly proportional to its frequency. This relationship is described by the equation E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency of the photon. In other words, as the frequency of a photon increases, its energy also increases.

Yes, you are correct! The energy of a photon is indeed directly proportional to its frequency. This relationship is known as the Planck-Einstein equation, given by:

E = hν

In this equation, E represents the energy of the photon, h is the Planck constant (approximately 6.626 x 10^(-34) Joule-seconds), and ν represents the frequency of the photon.

To find this relationship, you would need to refer to the field of physics and specifically quantum mechanics. The Planck-Einstein equation is derived from one of the key principles of quantum mechanics, which states that energy is quantized into discrete packets called photons. The equation relates the energy carried by a photon to its associated frequency.

So, in summary, as the frequency of a photon increases, its energy also increases proportionally according to the Planck-Einstein equation.