Light as Electromagnetic Radiation (4D) Practice Test

Two coherent laser beams of the same wavelength overlap on a detector, producing alternating bright and dark regions as the path length difference is varied. The total measured intensity at a point can be greater than the intensity from either beam alone. Which conclusion about light’s behavior is most consistent with this observation?

A researcher studies photodamage in cultured skin cells exposed for equal time to equal radiant power of 320 nm UV light or 520 nm visible light. More DNA lesions are observed after 320 nm exposure. Using $c = 3.0\times 10^8\ \text{m/s}$ and $h = 6.6\times 10^{-34}\ \text{J·s}$, which prediction aligns with the behavior of electromagnetic radiation and best explains the result?