diffraction gratings - 2026 ACF Regionals

Question

The spiral grooves on a compact disk make them act as these devices, explaining their iridescence. For 10 points each:

[10m] Name these devices that, like prisms, are commonly used to separate light in a monochromator.

ANSWER: diffraction gratings

[10e] A grating prism combination called a grism keeps only light of a specific value of this quantity undeviated. This quantity symbolized lambda equals wave speed over frequency.

ANSWER: wavelength

[10h] This type of diffraction grating is grooved at a namesake angle to maximize diffraction in a specific order. A specific type of these gratings are used in the HARPS (“harps”) spectrograph for exoplanet hunting.

ANSWER: blazed gratings [or echellette (“eh-shell-ET”) gratings; accept blaze angle; accept echelle (“eh-SHELL”) gratings]

<Purdue, Physics>

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Summary


California (North)	Main Site	Y	3	16.67	100%	67%	0%
California (South)	Main Site	Y	4	12.50	100%	25%	0%
Canada	Main Site	Y	12	12.50	100%	17%	8%
Florida	Main Site	Y	3	10.00	100%	0%	0%
Great Lakes	Main Site	Y	5	22.00	100%	80%	40%
Lower Mid-Atlantic	Main Site	Y	9	10.00	89%	11%	0%
Midwest	Main Site	Y	8	11.25	88%	25%	0%
Overflow	Main Site	Y	4	15.00	100%	50%	0%
South Central	Main Site	Y	2	15.00	100%	50%	0%
Southeast	Main Site	Y	7	10.00	71%	14%	14%
UK	Main Site	Y	12	13.33	92%	33%	8%
Upper Mid-Atlantic	Main Site	Y	8	10.00	75%	13%	13%
Upstate NY	Main Site	Y	4	12.50	100%	25%	0%

Data


Berkeley D	Berkeley B	0	10	0	10
Stanford A	Berkeley A	10	10	0	20
UC Irvine	UCSD B	0	10	0	10
UC Santa Barbara	Arizona State	0	10	0	10
UCLA A	UCSD A	10	10	0	20
UCLA B	UCSD C	0	10	0	10
Berkeley C	Stanford B	10	10	0	20
Toronto G	Brock	0	10	0	10
Guelph	Carleton University	0	10	0	10
McMaster B	Western B	0	10	0	10
McGill B	Toronto C	0	10	0	10
Toronto F	Toronto D	0	10	0	10
McGill A	Toronto E	0	10	0	10
Ottawa	UBC A	10	10	10	30
UBC B	Waterloo B	0	10	0	10
Queen's	Waterloo A	0	10	0	10
Toronto Metropolitan	Western A	0	10	0	10
Western C	Simon Fraser	0	10	0	10
Central Florida A	Florida B	0	10	0	10
Central Florida B	Florida A	0	10	0	10
Florida C	Central Florida C	0	10	0	10
CWRU B	Michigan C	10	10	0	20
Michigan A	CWRU A	10	10	10	30
Pittsburgh	Michigan B	0	10	0	10
Ohio State A	Ohio State B	10	10	10	30
Michigan State	Ohio State C	10	10	0	20
South Carolina B	Duke	0	10	0	10
James Madison B	North Carolina C	0	0	0	0
NC State B	Liberty A	0	10	0	10
NC State A	North Carolina A	10	10	0	20
James Madison A	North Carolina B	0	10	0	10
Liberty C	South Carolina A	0	10	0	10
VCU	Liberty B	0	10	0	10
Virginia Tech A	William and Mary	0	10	0	10
Virginia Tech B	Wake Forest	0	10	0	10
Northwestern C	Chicago A	0	10	0	10
Chicago C	Indiana B	0	10	0	10
Chicago D	Illinois C	10	10	0	20
Indiana A	Chicago E	10	10	0	20
Indiana C	Illinois A	0	0	0	0
Illinois B	Northwestern D	0	10	0	10
Purdue B	Notre Dame A	0	10	0	10
Notre Dame B	Chicago B	0	10	0	10
Georgia Tech A	Carleton College	0	10	0	10
Claremont	Missouri B	10	10	0	20
Missouri A	Iowa State	10	10	0	20
Washington B	Minnesota A	0	10	0	10
Texas A	Texas A&M A	10	10	0	20
Texas B	Murray State A	0	10	0	10
Kentucky	Alabama B	10	10	0	20
Georgia Tech B	Tennessee B	0	10	10	20
Louisville A	Bruin	0	0	0	0
Georgia Tech C	Sewanee	0	10	0	10
Vanderbilt B	Tennessee A	0	10	0	10
Louisville B	WashU A	0	10	0	10
Georgia Tech D	WashU B	0	0	0	0
Bristol	Cambridge C	0	10	0	10
Birmingham	Cardiff	0	10	0	10
Edinburgh A	Southampton A	10	10	0	20
City St. George's	Imperial A	0	0	0	0
LSE	Imperial C	0	10	0	10
Manchester	Imperial B	10	10	0	20
Montpellier	Cambridge A	0	10	0	10
Oxford A	Edinburgh B	10	10	10	30
Oxford B	Cambridge B	10	10	0	20
Durham	UCL	0	10	0	10
Warwick A	Oxford C	0	10	0	10
Southampton B	Warwick B	0	10	0	10
Maryland C	Catholic	0	10	0	10
Swarthmore	John Jay	0	0	0	0
Columbia C	Johns Hopkins A	10	10	0	20
Columbia B	Maryland A	0	10	0	10
NYU A	Georgetown	0	10	0	10
NYU B	Johns Hopkins B	0	10	0	10
Rutgers A	NYU C	0	10	10	20
Vassar	Rutgers B	0	0	0	0
RIT	Binghamton B	0	10	0	10
Cornell B	Penn State	0	10	0	10
Cornell C	Rochester	10	10	0	20
McMaster A	Toronto B	10	10	0	20
Cornell A	Binghamton A	0	10	0	10