Superconductors

Definition

Materials that, below a certain very low temperature, conduct electricity with zero electrical resistance and expel magnetic fields from their interior.

Key points

• Below the critical temperature, a superconductor carries current with no energy loss, so a current set up in a loop can persist almost indefinitely.
• They expel magnetic fields (the Meissner effect), which allows a magnet to float above a superconductor, the principle behind magnetic levitation (maglev) trains.
• The phenomenon was discovered by Heike Kamerlingh Onnes in 1911 (in mercury cooled with liquid helium).
• Conventional superconductors need extreme cooling; "high-temperature" superconductors work at higher (but still very cold) temperatures, and room-temperature superconductivity remains an unproven research goal (verify the latest claims).
• Uses include the powerful magnets in MRI machines and particle accelerators, maglev transport, and efficient power transmission.

Why it matters for CAPF

Superconductors, zero resistance, the Meissner effect, maglev, and their use in MRI machines are recurring physics and technology facts that appear in current affairs whenever new claims are reported.

Common confusion

A superconductor has exactly zero resistance, not merely very low resistance like a good ordinary conductor. "High-temperature" superconductors are still extremely cold by everyday standards; genuine room-temperature superconductivity has not been reliably confirmed.

Related concepts

concept semiconductors, concept quantum computing, concept alloys

Parent note

physics everyday