Answer :
Answer: a. the ability of certain substances at very low temperatures to conduct electricity with no resistance
Explanation:
Superconductivity is a property in certain materials where, when cooled below a characteristic critical temperature, they exhibit zero electrical resistance and expel magnetic fields. This allows them to conduct electricity perfectly without energy loss.
Let's see why the other options are incorrect:
b. "the ability of solid metals to conduct electricity in the presence of a magnetic field"
- This statement describes a general property of metals (conducting electricity) but does not specifically define superconductivity. Superconductivity is not just about conducting electricity - it is about doing so with zero resistance and the expulsion of magnetic fields (the Meissner effect).
c. "the ability of certain substances at very low temperatures to conduct electricity with low resistance"
- This statement mentions "low resistance," but superconductivity is characterized by zero resistance, not just low resistance. The defining feature of superconductors is that they completely eliminate electrical resistance below their critical temperature.
d. "the ability of solid metals to conduct electricity with low resistance in the presence of a magnetic field"
- This statement again talks about "low resistance" instead of zero resistance and incorrectly suggests that the presence of a magnetic field is a defining condition. While superconductors do interact with magnetic fields (they expel them due to the Meissner effect), their defining property is the zero electrical resistance.
The term "superconductivity" best refers to a) the ability of certain substances at very low temperatures to conduct electricity with no resistance.
Superconductivity is the phenomenon of certain materials conducting electricity with zero resistance at very low temperatures. This means there is no energy loss during electrical transmission in these materials.
This lack of resistance implies there is no energy loss when electricity flows through these materials. This is significant because it can lead to substantial reductions in the cost of electricity transmission. Hence, the correct option is a.
