Final answer:
The question is about the subject of Physics, where a ceramic superconducting material's transition into a superconducting state is induced by cooling it with liquid nitrogen. This demonstrates the practical use of superconductivity and cryogenics, particularly related to the cost and handling benefits of using liquid nitrogen as a coolant over liquid helium.
Step-by-step explanation:
The subject in the question pertains to the field of Physics, specifically to the topics of superconductivity and cryogenics. The context hints at the practical aspects of superconducting materials when cooled by liquid nitrogen. Superconductors exhibit remarkable properties such as zero electrical resistance and the expulsion of magnetic fields (Meissner effect) below their critical temperatures (Tc). The case given involves a ceramic superconductor with a mass of 0.25 kg being placed in liquid nitrogen to induce superconductivity, taking advantage of liquid nitrogen's boiling point at 77 K, which is within the range needed for some high-temperature superconductors to become superconducting.
Given the information that modern ceramic materials can become superconducting at temperatures close to 90 K, and considering that these temperatures can be achieved with liquid nitrogen, it suggests a focus on the economics and handling of superconducting materials. Moreover, understanding the properties of superconductors is instrumental in diverse applications ranging from MRIs to particle accelerators, and even in addressing the energy savings they might provide if used in electrical systems over traditional conductive materials.