Packet 7: Bonus 16
Albert Fert and Peter Grünberg discovered that this quantity depends on the magnetic field applied to iron chromide superlattices, leading to the development of spintronics. For 10 points each:
[10e] Name this quantity that equals voltage over current by Ohm’s law.
ANSWER: resistance [accept magnetoresistance or giant magnetoresistance; prompt on R]
[10m] Leo Esaki developed a type of these devices that achieves negative resistance due to quantum tunneling. On circuit diagrams, these devices are symbolized by a triangle pointing at a vertical line.
ANSWER: diodes [accept Esaki diodes]
[10h] In this effect, a “supercurrent” flows through a weak link at the junction between two superconductors. SQUIDs, which detect extremely small magnetic fields using this effect, are often used in dark matter detection experiments.
ANSWER: Josephson effect [accept Josephson junctions]
<Editors, Physics> | Packet G
| Editions | Heard | PPB | Easy % | Medium % | Hard % |
|---|---|---|---|---|---|
| 2 | 108 | 17.13 | 94% | 63% | 15% |
Conversion
| Team | Opponent | Part 1 | Part 2 | Part 3 | Total | Parts |
|---|---|---|---|---|---|---|
| Birmingham | Oxford | 10 | 10 | 0 | 20 | EM |
| Bristol | Warwick | 10 | 0 | 0 | 10 | E |
| Cambridge A | Imperial D | 10 | 10 | 0 | 20 | EM |
| Cambridge B | Cambridge D | 10 | 10 | 0 | 20 | EM |
| Cambridge E | Cambridge C | 10 | 10 | 0 | 20 | EM |
| Cardiff | LSE | 10 | 10 | 0 | 20 | EM |
| Imperial C | Imperial A | 10 | 10 | 0 | 20 | EM |
| Southampton | Imperial B | 10 | 10 | 0 | 20 | EM |
Summary
| Tournament | Edition | Exact Match? | Heard | PPB | Easy % | Medium % | Hard % |
|---|---|---|---|---|---|---|---|
| UK (North) | UK | Y | 5 | 22.00 | 100% | 100% | 20% |
| UK (South) | UK | Y | 8 | 18.75 | 100% | 88% | 0% |
| Northern California | US | Y | 4 | 17.50 | 100% | 75% | 0% |
| Southern California | US | Y | 7 | 21.43 | 100% | 86% | 29% |
| Eastern Canada (1) | US | Y | 4 | 15.00 | 75% | 50% | 25% |
| Eastern Canada (2) | US | Y | 9 | 13.33 | 89% | 11% | 33% |
| Florida | US | Y | 4 | 7.50 | 75% | 0% | 0% |
| Great Lakes | US | Y | 11 | 18.18 | 100% | 73% | 9% |
| Lower Mid-Atlantic | US | Y | 9 | 16.67 | 89% | 56% | 22% |
| Upper Mid-Atlantic | US | Y | 9 | 17.78 | 100% | 56% | 22% |
| Midwest | US | Y | 9 | 17.78 | 100% | 67% | 11% |
| North | US | Y | 4 | 12.50 | 75% | 50% | 0% |
| Pacific | US | Y | 8 | 21.25 | 100% | 88% | 25% |
| South Central | US | Y | 5 | 14.00 | 80% | 60% | 0% |
| Southeast | US | Y | 11 | 16.36 | 91% | 64% | 9% |
| Upstate NY | US | Y | 1 | 20.00 | 100% | 100% | 0% |