Final answer:
Beta particles, which are negatively charged, are deflected toward the positive plate when nuclear emissions pass through an electric field, due to the attraction between opposite charges.
Step-by-step explanation:
When nuclear emissions are passed through a positive and negative plate, beta particles are deflected toward the positive plate. This happens because beta particles are electrons that are ejected from the nucleus and carry a negative charge, symbolized by the Greek letter β. Since opposite charges attract, the negatively charged beta particles are drawn towards the positively charged plate. The significance of the attraction is more pronounced for beta particles than for alpha particles due to their much smaller mass. Alpha particles are positively charged and are attracted to the negative plate but are deflected only slightly because of their greater mass. Neutrons, being neutral, are unaffected by electric fields, as are gamma rays, which are also uncharged.