Final answer:
The primary difference between sealed and unsealed radiation is that sealed sources contain the radioactive material, preventing its spread, whereas unsealed radiation involves radioactive substances that can disperse into the environment.
Step-by-step explanation:
The #1 difference between sealed and unsealed radiation pertains to the containment of radioactive material. Sealed radiation sources are those in which radioactive material is securely enclosed, typically within a metal or some other durable casing, thus preventing the spread of radioactive particles into the environment. Common examples of sealed sources include medical therapy sources, industrial gauges, and certain types of smoke detectors. Unsealed radiation, on the other hand, involves radioactive material that is not contained and can readily disperse or mix with other materials, such as gases, liquids, or powders. These materials require careful handling to prevent contamination and exposure. The risk of inhaling or ingesting unsealed radioactive material can be significant, as with the case of radon, which is a radioactive gas capable of causing lung cancer with long-term exposure.