Which equation expresses energy in terms of frequency?

The equation that expresses energy in terms of frequency is derived from Planck's equation, which relates the energy of a photon to its frequency. According to this relationship, energy is directly proportional to frequency, with Planck's constant (h) serving as the proportionality factor. Thus, the formula can be stated as E = h * frequency.

This indicates that as the frequency of electromagnetic radiation increases, the energy associated with that radiation also increases. Each photon of light can be understood to carry a specific amount of energy that corresponds to its frequency, making this equation fundamental in fields such as quantum mechanics and photonics.

The other choices do not convey the correct relationship between energy and frequency. For example, the equation E = m * c^2 relates energy to mass and the speed of light, but does not incorporate frequency. The choice E = frequency / h suggests an incorrect mathematical relationship. Finally, E = h + frequency does not accurately reflect how energy and frequency interact, since energy depends multiplicatively on frequency rather than being summed with it.