Photon Energy Comparison: Electromagnetic Spectrum

The energy of a single photon is directly related to its frequency and inversely related to its wavelength. This relationship is described by the Planck-Einstein relations:

$E = hf$

where $E$ is the energy of the photon, $h$ is Planck's constant, and $f$ is the frequency of the radiation.

Alternatively, using the relationship between frequency ($f$), wavelength ($\lambda$), and the speed of light ($c$), $f = \frac{c}{\lambda}$, the energy can be expressed as:

$E = \frac{hc}{\lambda}$

This means higher frequency or shorter wavelength radiation corresponds to higher energy per photon.

Electromagnetic Spectrum Ordering

The given types of electromagnetic radiation are ordered by increasing energy (and frequency, decreasing wavelength) as follows:

1. Infra-red ray (Lowest energy)
2. Visible-ray
3. Ultra-violet ray
4. X-ray (Highest energy)

Identifying Highest Energy Photon

Based on their position in the electromagnetic spectrum, X-rays have the highest frequency and shortest wavelength among the given options. Therefore, X-rays possess the largest energy per photon.