20100228

Astronomy current events question: Solar Dynamics Observatory launch

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
NASA news release, "New Eye on the Sun," February 11, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=9416
NASA's Solar Dynamics Observatory was recently launched, and its mission is to:
(A) understand the effect of the sun on Earth's atmosphere and climate.
(B) detect the presence of dark matter within sunspots.
(C) shield Earth from global warming from the sun.
(D) determine how much longer the sun will live, before becoming a red giant.
(E) observe the effect of high energy particle beams directed onto solar flares.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 1 student
(B) : 3 students
(C) : 19 students
(D) : 37 students
(E) : 3 students

20100227

Astronomy current events question: Mars Express Phobos flyby

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
European Space Agency news release, "Phobos' Flyby Season Starts Again," February 17, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=9437
The European Space Agency Mars Express spacecraft will soon pass very near Phobos, the largest moon of Mars, in order to:
(A) look for remnants of the failed Russian Mars probe Phobos 2.
(B) slingshot itself over to Deimos, the smallest moon of Mars.
(C) look for ice hidden in shadowed craters on its polar caps.
(D) map Phobos' gravity field, and deduce its internal structure.
(E) detect the presence of organic molecules.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 0 students
(B) : 3 students
(C) : 2 students
(D) : 27 students
(E) : 1 student

20100226

Found physics: B-type 67.5 volt battery

20100220484
http://www.flickr.com/photos/waiferx/4373720517/
Originally uploaded by Waifer X


20100220484
http://www.flickr.com/photos/waiferx/4373720519/
Originally uploaded by Waifer X

Eveready(TM) "B" type battery, 67.5 volts. "Always test 'B' batteries with a voltmeter—NEVER an ammeter." Photo by Cuesta College Physical Sciences Division instructor Dr. Patrick M. Len.

20100225

Astronomy quiz question: evidence contradicting Earth-centered universe

Astronomy 210 Quiz 2, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

__________ made observations that were used as evidence that Earth could not be center of motion in the universe.
(A) Copernicus.
(B) Tycho.
(C) Kepler.
(D) Galileo.

Correct answer: (D)

While Copernicus placed the sun at the center of the planetary orbits, his model was not based on observations. Kepler analyzed Tycho's observations to come with empirical laws that accurately described planetary motion along elliptical orbits. Galileo's observations of Jupiter's moons, and Venus' gibbous phases were used as evidence that Earth was not the sole center of motion in the universe. However, Galileo's observations cannot be taken as evidence that Earth moves about the sun...

Section 30676
(A) : 22 students
(B) : 15 students
(C) : 10 students
(D) : 27 students

"Success level": 40% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

20100224

Physics quiz question: telescope construction

Physics 205B Quiz 2, spring semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 24.49(b)

Two converging lenses, with focal lengths of +90 cm and +1.5 cm, are to be used to make a telescope.

The _________ lens and the _________ lens should be used as the objective and the eyepiece, respectively, in order to make a telescope with the greatest amount of magnification.
(A) f = +1.5 cm; f = +90 cm.
(B) f = +90 cm; f = +1.5 cm.
(C) (The order of the lenses is not important.)
(D) (Not enough information is given.)

Correct answer (highlight to unhide): (B)

The angular magnification of the telescope using two converging lenses is given by:

M = –fo/fe,

such to obtain the greatest possible angular magnfication, the objective should be the longer focal length lens, and eyepiece should be shorter focal length lens.

Student responses
Section 31988
Exam code: quiz02L3n5
(A) : 1 student
(B) : 11 students
(C) : 0 students
(D) : 0 students

Success level: 91%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.20

20100223

Physics quiz question: simple magnifier

Physics 205B Quiz 2, spring semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 24.29

A Physics 205B student would like to use a lens from +5.0 D reading glasses as a simple magnifier. What is the angular magnification of this lens as used by a relaxed eye?
(A) +0.80.
(B) +1.3.
(C) +5.0.
(D) +20.

Correct answer: (B)

The angular magnification of a converging lens used as a simple magnifier (eyepiece) is given by:

M = N/f,

where N = 0.25 m is the nominal near point, and f is the focal length (in m) of the lens, which is the reciprocal of the refractive ("optical") power P (in diopters, D or m-1). Thus:

M = N/f = N·P = (0.25 m)·(+5.0 m-1) = +1.25,

or +1.3, to two significant figures.

Response (A) is f/N = 1/(P·N); response (C) is the refractive power P; and response (D) is P/N = 1/(f·N).

Student responses
Section 31988
(A) : 0 students
(B) : 5 students
(C) : 4 students
(D) : 3 students

Success level: 41%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.60

20100222

Astronomy current events question: Cassini mission extended

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
United Press International, "NASA Extends Cassini Tour of Saturn," February 3, 2010
http://www.skyandtelescope.com/news/wires?id=140832154&c=y
What has NASA planned for the Cassini space probe in orbit around Saturn?
(A) Moving it to rendevous with Pluto in 2012.
(B) Extending its operation through 2017.
(C) Crashing into Saturn's atmosphere to gather data on its composition.
(D) Parking it in Saturn's rings until its operating budget can be restored.
(E) Sending it out of the solar system after one last pass near Saturn.

Correct answer: (B)

Student responses
Sections 30678, 30679, 30680
(A) : 1 student
(B) : 50 students
(C) : 3 students
(D) : 5 students
(E) : 4 students

20100221

Astronomy current events question: asteroid collision

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Astronomy.com editors, "Suspected asteroid collision leaves trailing debris," February 2, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=9113
Researchers at the University of California, Los Angeles suspect that the comet-like object P/2010 A2 in the asteroid belt is:
(A) rich with organic compounds.
(B) from the trailing, unstable edge of the asteroid belt.
(C) on a collision course with Earth in late 2012.
(D) an icy asteroid that has begun to absorb too much sunlight.
(E) the result of a head-on collision between two asteroids.

Correct answer: (E)

Student responses
Sections 30678, 30679, 30680
(A) : 2 students
(B) : 8 students
(C) : 1 student
(D) : 1 student
(E) : 51 students

20100220

Astronomy current events question: Pluto color changes

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Kelly Beatty, "New Face of Pluto," February 4, 2010
http://www.skyandtelescope.com/news/home/83606532.html
Recent images from the Hubble Space Telescope show that Pluto:
(A) has undergone rapid color changes on its surface.
(B) is much too small to reconsidered as a planet.
(C) has melted its polar ice caps.
(D) experienced a total solar eclipse from one of its moons, Charon.
(E) is spinning much faster than previously measured.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 51 students
(B) : 4 students
(C) : 3 students
(D) : 2 students
(E) : 4 students

20100219

Overheard: scotch tape

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

(Overheard in introductory astronomy lab.)

Instructor: "Use lots of scotch tape. Scotch tape is the duct tape of astronomy."

20100218

Astronomy quiz question: inferior planets at midnight

Astronomy 210 Quiz 2, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Why are Mercury and Venus never visible in the San Luis Obispo, CA sky at midnight?
(A) Mercury and Venus never exhibit retrograde motion.
(B) Mercury and Venus are too small to reflect enough sunlight.
(C) The orbits of Mercury and Venus are smaller than the orbit of Earth.
(D) Mercury and Venus cannot exhibit gibbous phases.

Correct answer: (C)

Since the orbits of Mercury and Venus are smaller than the orbit of Earth (making them inferior planets), they can never appear behind Earth, with respect to the sun, and thus cannot be overhead (or anywhere in the sky) at midnight for typical temperate latitudes such as for San Luis Obispo, CA.

Student responses
Section 30674
(A) : 4 students
(B) : 5 students
(C) : 34 students
(D) : 2 students

Success level: 78% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.71

Student responses
Section 30676
(A) : 10 students
(B) : 8 students
(C) : 45 students
(D) : 11 students

Success level: 64% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.85

Previous posts:

20100217

Astronomy quiz question: partial lunar eclipse

Astronomy 210 Quiz 2, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

What would be seen by an observer on the side of Earth facing the moon, during a partial lunar eclipse?
(A) The entire sun blocked by a new moon.
(B) Part of the sun will be blocked by a new moon.
(C) A new moon that will not be big enough to entirely block the sun when it passes in front of it.
(D) A full moon that will appear a very, very dark brown-red.
(E) A dark shadow across part of a full moon.
(F) A full moon that will appear to be slightly dimmer than usual.

Correct answer: (D)

During a partial lunar eclipse, an observer on Earth will see the full moon partly in Earth's umbra and penumbra, where the umbra portion will be dark, while the penumbra portion will not be noticeably dimmer.

Section 30674
(A) : 1 student
(B) : 10 students
(C) : 4 students
(D) : 0 students
(E) : 28 students
(F) : 1 student
(Blank: 1 student)

Success level: 66% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.64

20100216

Online homework assignment: destructive thin film reflections

Physics 205B Homework Assignment 4, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 25.17

A thin film of oil (n = 1.50) of thickness 0.40e-6 m is spread over a puddle of water (n = 1.33). The two visible wavelengths that will destructively interfere for reflection will have values of __________ nm and __________ nm in air. (Visible wavelengths in air are in the range of 400 nm to 700 nm.)

Correct answer: 400 nm, 600 nm.

Light in air reflects off of the top of the oil film with a 180 degree phase shift ("fast off of slow"). Light in oil reflects off the top of the water with no phase shift ("slow off of fast"). The two reflections are out of phase.

For destructive interference of these two out of phase reflections, the path difference condition is:

delta(l) = m*lambda_oil,

where the path difference between the two reflected waves is twice the thickness of the oil film, or 2*t, and lambda_oil is related to the lambda_air wavelengths in air:

lambda_oil = lambda_air/n_oil,

as wavelengths are shorter in slower media, compared to the longest in air (or vacuum).

Substituting delta(l) = 2*t, and lambda_oil = lambda_air/n_oil into the destructive interference condition for out of phase reflections:

2*t = m*(lambda_air/n_oil),

2*t*n_oil/m = lambda_air,

with m = 0, 1, 2, 3, 4, ..., possible wavelengths in air that would destructively interfere would be infinite, 1200 nm, 600 nm, 400 nm, 300 nm, ..., respectively, of which only 400 nm and 600 nm are in the visible range in air.

Student responses
Section 31988
537 nm, 637 nm: 1 response
400 nm, 600 nm: 2 responses
429 nm, 687 nm: 1 response
(Blank/no work submitted: 9 responses)

20100215

Found physics: hair diffraction pattern

100212-1140932
http://www.flickr.com/photos/waiferx/4351928565/
Originally uploaded by Waifer X

Laser illuminating a tape-mounted human hair, with the resulting diffraction pattern projected on a distant screen. Photo by Cuesta College Physical Sciences Division instructor Dr. Patrick M. Len.

20100214

Found physics: hair diffraction diagnostic test

100212-1140924
http://www.flickr.com/photos/waiferx/4351922065/
Originally uploaded by Waifer X

Dramatization of "Fermiscan®" x-ray diffraction of human hairs, being developed as a diagnosis tool for screening for breast cancer. All rights reserved by original copyright holders. Photo-montage by Cuesta College Physical Sciences Division instructor Dr. Patrick M. Len.

20100213

Found physics: varying double slit separation distance

100207-1140877
http://www.flickr.com/photos/waiferx/4344082697/
Originally uploaded by Waifer X

Increasing, then decreasing the spacing d between two slits illuminated by a laser beam, resulting in decreasing, then increasing the angular spacing between maxima and minima fringes on a distant screen. Video by Cuesta College Physical Sciences Division instructor Dr. Patrick M. Len.

20100212

Astronomy current events question: recurrent U Scorpii nova

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Astronomy.com editors, "Long-Anticipated Eruption of U Scorpii Has Begun," January 28, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=9020
U Scorpii is a star that is starting a recurrent nova explosion. What causes this?
(A) A star is feeding hydrogen onto the outer layers of a white dwarf.
(B) The core of a massive star has finally exhausted its hydrogen supply.
(C) The eruption of magnetic fields surrounding an unstable supergiant.
(D) Too much iron in the core of a supergiant.
(E) Bipolar jets from a companion neutron star.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 45 students
(B) : 13 students
(C) : 6 students
(D) : 1 student
(E) : 3 students

20100211

Astronomy current events question: listening for Phoenix lander

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Alicia Chang (Associated Press), "NASA Listens for Silent Mars Lander," January 17, 2010
http://www.skyandtelescope.com/news/wires?id=140109382&c=y
NASA will begin listening for signals from the Phoenix lander on Mars, which has been silent since November 2008 because:
(A) of budget cuts.
(B) it was buried by layers of dry ice.
(C) of a software failure.
(D) its radio dish is stuck pointing in one direction only.
(E) it was quietly listening for signs of intelligent life.

Correct answer: (B)

Student responses
Sections 30678, 30679, 30680
(A) : 1 student
(B) : 30 students
(C) : 2 students
(D) : 3 students
(E) : 0 students

20100210

Astronomy current events question: Spirit rover now lander

Astronomy 210L, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Kelly Beatty, "Spirit Morphs into a Martian Lander," January 26, 2010
http://www.skyandtelescope.com/news/82759442.html
Because the NASA Mars Spirit rover is stuck, it will:
(A) become buried by shifting sands caused by winter windstorms.
(B) sink further into quicksand-like material.
(C) keep transmitting its location, so Mars' rotation can be tracked.
(D) drill further into a nearby rock to investigate its core.
(E) wait until the Mars Opportunity rover arrives to give it a nudge.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 7 students
(B) : 1 student
(C) : 21 students
(D) : 1 student
(E) : 2 students

20100209

Astronomy quiz question: astrological sun-sign date discrepancy

Astronomy 210 Quiz 1, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Earth's __________ causes the discrepancy between astrological sun-sign dates and the dates when the sun is actually in front of certain zodiac constellations.
(A) rotation.
(B) revolution.
(C) precession.
(D) tilt.

Correct answer: (C)

Section 30676
(A) : 6 students
(B) : 20 students
(C) : 45 students
(D) : 9 students

Success level: 59% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.69

20100208

Physics quiz question: finding incident angle from transmitted angle

Physics 205B Quiz 1, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 23.11

Sunlight strikes the surface of a lake (index of refraction 1.33). A fish sees the sun underwater at an angle of 30.0° with respect to the normal. What angle do the sun's rays in air make with respect to the normal? (Drawing is not to scale.)
(A) 22.1 degrees.
(B) 40.6 degrees.
(C) 41.7 degrees.
(D) 48.8 degrees.

Correct answer: (C)

From Snell's law, n_i*sin(theta_i) = n_t*sin(theta_t), where n_i = 1.000 (given), n_t = 1.33, and theta_t = 30.0 degrees. Then solving for the incident angle in air:

theta_i = Arcsin(n_t*sin(theta_t)/n_i) = 41.7 degrees.

Response (A) is Arcsin(sin(theta_t)/n_t); response (B) is Arcsin(sin(90 degrees - theta_t)/n_t); response (D) is Arcsin(n_i/n_t), which is the critical angle for water incident on air.

Student responses
Section 31988
(A) : 2 students
(B) : 0 students
(C) : 10 students
(D) : 1 student

Success level: 76%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

20100207

Physics quiz question: unpolarized light transmitted through two polarizers

Physics 205B Quiz 1, spring semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 22.45

Unpolarized light passes through two polarizers with polarization axes turned 40° to one another.


The fraction of the incident light intensity transmitted is:
(A) 0.21.
(B) 0.29.
(C) 0.41.
(D) 0.59

Correct answer (highlight to unhide): (B)

The intensity of light that passes through polarizer 1 is one-half of the original unpolarized intensity, and this light is then vertically polarized (the convention followed in this class is to depict transmission axes of polarizers).

The fraction of the vertically polarized light that passes through polarizer 2 is:

cos2(40°) = 0.58682408883...,

thus the light that passes through both polarizer 1 and polarizer 2 is:

(1/2)·(0.58682408883...) = 0.29341204442...,

or to two significant figures, 0.29 of the original unpolarized intensity.

(Response (A) is (1/2)·sin2(40°), response (C) is sin2(40°), and response (D) is cos2(40°).)

Student responses
Section 31988
Exam code: quiz01sN3L
(A) : 3 students
(B) : 7 students
(C) : 1 student
(D) : 2 students

Success level: 53%
Discrimination index (Aubrecht & Aubrecht, 1983): 1.00

20100206

Physics quiz question: frequency of light, given wavelength

Physics 205B Quiz 1, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 22.13

Light has a wavelength of 600 nm as it travels through air. What is the frequency of this light?
(A) 2.0e-15 Hz.
(B) 180 Hz.
(C) 1.7e6 Hz.
(D) 5.0e14 Hz

Correct answer: (D)

The dependent parameter lambda = v/f, where the independent parameters v and f correspond to the speed the frequency, respectively. Thus f = v/lambda = (3.00e8 m/s)/(600e-9 m) = 5.0e14 s^-1, or Hz. (The speed of light in vacuum was provided, as well as the index of refraction for air n_air = 1.000.) Response (A) is lambda/v, response (B) is c*lambda, and response (C) is 1/lambda.

Student responses
Section 31988
(A) : 2 students
(B) : 0 students
(C) : 2 students
(D) : 9 students

Success level: 69%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.75

20100205

Astronomy quiz question: diurnal motion of circumpolar constellation

Astronomy 210 Quiz 1, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

[Version 1]
The constellation Cepheus is located below the star Polaris and just above the north horizon, as seen by an observer on February 3 in San Luis Obispo, CA. (Ignore the fact that your starwheel does not include daylight saving time.) Within the next 24 hours, this observer will notice that the constellation Cepheus:
(A) moves clockwise around Polaris, and never sets below the horizon.
(B) moves counterclockwise around Polaris, and never sets below the horizon.
(C) moves clockwise around Polaris, and sets below the horizon.
(D) moves counterclockwise around Polaris, and sets below the horizon.

Correct answer: (B)

Using a starwheel for 40° northern latitudes (San Luis Obispo, CA is 35° N latitude) shows Cepheus is a circumpolar constellation, never setting below the horizon, and makes counterclockwise circles around the north celestial pole (near Polaris).

Section 30674
(A) : 7 students
(B) : 34 students
(C) : 0 students
(D) : 0 students
(Blank): 1 student

Success level: 67% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.61

[Version 2]
The constellation Camelopardalis is located at its highest point in the sky, as seen by an observer on February 3 in San Luis Obispo, CA. (Ignore the fact that your starwheel does not include daylight saving time.) Within the next 24 hours, this observer will notice that the constellation Camelopardalis:
(A) moves clockwise around Polaris, and never sets below the horizon.
(B) moves counterclockwise around Polaris, and never sets below the horizon.
(C) moves clockwise around Polaris, and sets below the horizon.
(D) moves counterclockwise around Polaris, and sets below the horizon.

Correct answer: (B)

Using a starwheel for 40° northern latitudes (San Luis Obispo, CA is 35° N latitude) shows Camelopardalis is a circumpolar constellation, never setting below the horizon, and makes counterclockwise circles around the north celestial pole (near Polaris).

Section 30676
(A) : 13 students
(B) : 50 students
(C) : 5 students
(D) : 12 students

Success level: 65% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.59

20100204

Astronomy quiz question: sunset/sunrise location

Astronomy 210 Quiz 1, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

[Version 1]
On a certain day an observer in San Luis Obispo, CA notices that there are 10 hours between sunrise and sunset. On this day, the sun will set on the horizon at a point:
(A) between northeast and east.
(B) due east.
(C) between east and southeast.
(D) between southwest and west.
(E) due west.
(F) between west and northwest.

Correct answer: (D)

10 hours between sunrise and sunset means winter solstice for San Luis Obispo, CA (or in general for any northern hemisphere location, sometime between autumnal equinoxes and vernal equinoxes), meaning that the sun must rise from south of east, and set south of west.

Section 30674
(A) : 4 students
(B) : 0 students
(C) : 3 students
(D) : 29 students
(E) : 5 students
(F) : 5 students

Success level: 67% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.61

[Version 2]
On a certain day an observer in San Luis Obispo, CA notices that there are 14 hours between sunrise and sunset. On this day, the sun rose on the horizon at a point:
(A) between northeast and east.
(B) due east.
(C) between east and southeast.
(D) between southwest and west.
(E) due west.
(F) between west and northwest.

Correct answer: (D)

14 hours between sunrise and sunset means summer solstice for San Luis Obispo, CA (or in general for any northern hemisphere location, sometime between vernal equinoxes and autumnal equinoxes), meaning that the sun must rise from north of east, and set north of west.

Section 30676
(A) : 39 students
(B) : 9 students
(C) : 9 students
(D) : 8 students
(E) : 2 students
(F) : 6 students

Success level: 53% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.69

20100203

Astronomy quiz question: Earth's rotation

Astronomy 210 Quiz 1, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Earth's rotation causes the sun to:
(A) appear in front of different zodiac constellations.
(B) move from east to west across the sky during the day.
(C) make higher or lower paths across the sky.
(D) (None of the above choices.)

Correct answer: (B)

Section 30674
(A) : 7 students
(B) : 36 students
(C) : 2 students
(D) : 1 student

Success level: 80% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.38

20100202

Misprint: first or third quarter moon?

100131-1140788
http://www.flickr.com/photos/waiferx/4319990633/
Originally uploaded by Waifer X

Comparison of misprinted and corrected versions of lunar phase cycle, Michael A. Seeds and Dana E. Backman, Perspectives in Astronomy, 1/e, Brooks/Cole, 2008, p. 25. Photo by Cuesta College Physical Sciences Division instructor Dr. Patrick M. Len.

20100201

Found physics: simple magnifier


100130-1140785
http://www.flickr.com/photos/waiferx/4317202635/
Originally uploaded by Waifer X

Wire cutters brought closer to enlarge its angular size, but much closer than the near point of the camera lens (focused at infinity to simulate a relaxed eye). A magnifying glass is then placed in front of the camera lens to project a virtual image of this wire cutters out at infinity, which subsequently becomes an object for the camera lens to be able to focus on. Photo by Cuesta College Physical Science instructor Dr. Patrick M. Len.