The ray that is not affected by magnetic and electromagnetic fields is gamma rays.

Here's why:

* Gamma rays are a form of electromagnetic radiation, but they are incredibly high-energy photons. This means they have no charge and are not affected by magnetic or electric fields.

* Other rays like alpha and beta rays are made of charged particles (alpha particles are helium nuclei, beta particles are electrons or positrons). These particles are strongly affected by magnetic and electric fields.

Let me know if you'd like more details about any of these!