Which material offers no resister with flow of charges below a certain critical temperature?
a. conductor
b. insuiator
C. semiconducters
d. superconductor
The correct answer and explanation is:
The correct answer is d. superconductor.
Explanation:
A superconductor is a material that offers no resistance to the flow of electric charge (current) below a certain critical temperature. This phenomenon is known as superconductivity, which occurs when the material is cooled to a temperature near absolute zero or below its critical temperature. At this point, the electrical resistance of the material drops to zero, allowing electric current to flow without any energy loss.
Superconductivity was first discovered in 1911 by Heike Kamerlingh Onnes in mercury, where it was observed that the material’s resistance completely vanished below a certain temperature. Since then, many other materials have been found to exhibit superconductivity, including elements like lead and niobium, and compounds like yttrium barium copper oxide (YBCO).
In contrast:
- Conductors, like copper and aluminum, have low resistance to the flow of electric charge, but their resistance does not vanish, even at very low temperatures.
- Insulators, such as rubber or glass, have very high resistance and prevent the flow of charge under normal conditions.
- Semiconductors (like silicon) have moderate resistance that can be controlled by external factors such as temperature, doping, or electric fields. At low temperatures, semiconductors typically behave as insulators, but their conductivity can be enhanced as the temperature rises.
The absence of electrical resistance in superconductors leads to potential applications in various fields such as magnetic levitation (as seen in maglev trains), medical imaging (e.g., MRI machines), and quantum computing. However, a major limitation is the requirement for very low temperatures to maintain the superconducting state, which makes their widespread use expensive and challenging.