resistance - 2025 ACF Fall

Question

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>

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Summary


Northern California	Main	Y	4	17.50	100%	75%	0%
Southern California	Main	Y	7	21.43	100%	86%	29%
Eastern Canada (1)	Main	Y	4	15.00	75%	50%	25%
Eastern Canada (2)	Main	Y	9	13.33	89%	11%	33%
Florida	Main	Y	4	7.50	75%	0%	0%
Great Lakes	Main	Y	11	18.18	100%	73%	9%
Lower Mid-Atlantic	Main	Y	9	16.67	89%	56%	22%
Upper Mid-Atlantic	Main	Y	9	17.78	100%	56%	22%
Midwest	Main	Y	9	17.78	100%	67%	11%
North	Main	Y	4	12.50	75%	50%	0%
Pacific	Main	Y	8	21.25	100%	88%	25%
South Central	Main	Y	5	14.00	80%	60%	0%
Southeast	Main	Y	11	16.36	91%	64%	9%
UK (North)	UK	Y	5	22.00	100%	100%	20%
UK (South)	UK	Y	8	18.75	100%	88%	0%
Upstate NY	Main	Y	1	20.00	100%	100%	0%

Data


Berkeley Skeleton King	UCSC	10	10	0	20
Stanford A	Berkeley Archer Queen	10	0	0	10
Berkeley Boss Bandit	Berkeley Mighty Miner	10	10	0	20
Berkeley Little Prince	Stanford B	10	10	0	20
Claremont C	USC A	10	0	0	10
Claremont B	UC Santa Barbara	10	10	0	20
Claremont A	UCLA A	10	10	10	30
UCLA B	UCLA C	10	10	10	30
UCSD A	UCLA E	10	10	0	20
UCSD B	UCLA F	10	10	0	20
UCLA D	USC B	10	10	0	20
Carleton A	Ottawa B	10	10	0	20
McGill B	Ottawa C	10	10	10	30
Ottawa A	Ottawa D	10	0	0	10
McGill E	Carleton B	0	0	0	0
Guelph A	Toronto A	10	0	0	10
McMaster A	Toronto C	10	0	10	20
Waterloo A	McMaster B	10	10	10	30
Toronto B	Queen's A	10	0	0	10
Toronto E	Waterloo C	10	0	10	20
Brock A	Toronto F	10	0	0	10
Toronto D	Toronto H	10	0	0	10
Toronto I	Toronto G	0	0	0	0
McMaster C	Waterloo B	10	0	0	10
Florida A	Florida Tech B	0	0	0	0
Florida B	Florida Tech A	10	0	0	10
UCF A	South Florida A	10	0	0	10
Florida State A	ERAU Daytona A	10	0	0	10
Michigan State B	Louisville B	10	0	0	10
CWRU A	CWRU D	10	0	0	10
Ohio State C	Kentucky	10	10	0	20
Michigan B	Michigan State D	10	10	0	20
Michigan C	Michigan State C	10	10	0	20
Ohio State A	Michigan D	10	10	0	20
Louisville D	Michigan State A	10	10	0	20
CWRU B	Pittsburgh	10	10	0	20
Louisville A	WVU A	10	10	10	30
WVU B	Ohio State D	10	0	0	10
Louisville C	Ohio State B	10	10	0	20
William & Mary A	Liberty A	10	10	0	20
Virginia Tech B	JMU A	10	10	0	20
Virginia Tech C	NCSU A	10	0	0	10
NCSU B	UNC A	0	0	0	0
VCU A	Tusculum A	10	10	0	20
Virginia Tech A	UNC B	10	0	10	20
Virginia A	UNC D	10	10	10	30
Duke A	William & Mary C	10	10	0	20
Liberty C	Liberty B	10	0	0	10
George Mason A	Lehigh A	10	0	10	20
Johns Hopkins	Maryland C	10	10	0	20
Princeton	NYU B	10	10	10	30
Rutgers A	Lehigh B	10	0	0	10
Rutgers B	NYU C	10	10	0	20
Rutgers C	Maryland A	10	10	0	20
Rutgers D	Rowan	10	0	0	10
George Mason B	Stony Brook	10	0	0	10
Maryland B	Vassar B	10	10	0	20
Illinois Urbana	Chicago A	10	0	0	10
Purdue C	Chicago B	10	10	0	20
Illinois Canada	Purdue D	10	0	0	10
Illinois Champaign	Rose-Hulman A	10	10	0	20
Illinois Orange	Iowa A	10	10	10	30
Indiana A	Iowa B	10	0	0	10
Purdue A	Indiana B	10	10	0	20
Illinois Blue	WashU Grolars	10	10	0	20
Purdue B	William Woods University A	10	10	0	20
Iowa State	Minnesota	10	10	0	20
Macalester	Michigan Tech	10	10	0	20
Wisconsin B	Wisconsin A	0	0	0	0
St. Thomas	Wisconsin C	10	0	0	10
Arizona State B	Washington Atlantic	10	10	10	30
Arizona State A	Washington Chum	10	10	0	20
Washington State	Boise State	10	10	0	20
Alberta A	British Columbia A	10	10	10	30
Washington Steelhead	British Columbia B	10	10	0	20
Washington Chinook	Texas	10	0	0	10
Washington Pink	British Columbia C	10	10	0	20
Alberta B	Washington Sockeye	10	10	0	20
Rose State	Kansas State A	0	0	0	0
Murray State College A	Nebraska A	10	0	0	10
Nebraska B	Oklahoma	10	10	0	20
Tulsa A	Harding	10	10	0	20
Central Oklahoma A	Tulsa B	10	10	0	20
Auburn C	Vanderbilt C	10	10	0	20
Alabama A	South Carolina A	10	0	0	10
Georgia Tech D	Clemson C	10	10	0	20
Georgia A	Tennessee B	0	0	0	0
Georgia Tech B	Georgia Tech E	10	10	0	20
Emory A	Georgia Tech C	10	0	0	10
Georgia Tech F	Mississippi State A	10	10	0	20
Clemson B	Sewanne	10	0	0	10
Chipola College	Tennessee Tech	10	10	10	30
Vanderbilt A	Tennessee A	10	10	0	20
Georgia Tech A	Clemson A	10	10	0	20
Durham D	Durham A	10	10	10	30
Durham C	Durham B	10	10	0	20
Edinburgh D	Edinburgh B	10	10	0	20
Sheffield B	Edinburgh A	10	10	0	20
York	Sheffield A	10	10	0	20
Cambridge E	Cambridge C	10	10	0	20
Cambridge B	Cambridge D	10	10	0	20
Southampton	Imperial B	10	10	0	20
Imperial C	Imperial A	10	10	0	20
Cambridge A	Imperial D	10	10	0	20
Birmingham	Oxford	10	10	0	20
Bristol	Warwick	10	0	0	10
Cornell D	RIT A	10	10	0	20
Cardiff	LSE	10	10	0	20