A photon of frequency $50\text{Hz}$ possesses _________ $\text{J}$ energy. (where $h$ is Planck's constant and $c$ is the speed of light in vacuum)

According to Planck's quantum theory, the energy ($E$) of a photon is directly proportional to its frequency ($\nu$) and is given by the formula:
$$E=h\nu$$

Given that the frequency $\nu =50\text{Hz}$:

$$E=h\times 50=50h\text{J}$$