Physics quiz archive: interference, electrostatics

Physics 205B Quiz 3, spring semester 2020
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz03Cv1d



Sections 30882, 30883 results

0- 6 :
7-12 :
13-18 :	**** [low = 15]
19-24 :	***************
25-30 :	*************** [mean = 24.2 +/- 4.2] [high = 30]

Online reading assignment: double-slit interference

Physics 205B, spring semester 2020
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on double-slit interference.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"For in-phase sources, the difference in path length will be a whole number of wavelengths for constructive interference. For destructive interference the path difference will be (a whole number plus) a half of a wavelength."

"The presentation did a good job at conveying the path differences for the double slits. It was defined clearly."

"I understand from this section that the maxima and minima of a double-slit interference means whether or not it is constructive or destructive. this is determined by various variables of a double-slit interference like the wavelength, distance between slits, etc."

"Young's double-slit experiment showed how two monochromatic light sources could interfere constructively and destructively. This was shown by the alternating dark and light fringes on the screen he used."

"The difference in lengths that parallel waves travel is equal to their separation distance d between multiplied by sinθ. The inner wave also travels farther."

"In double-slit interference θ is measured from the horizontal and ranges from –90° to +90° with 0° deg being horizontal. The equation dsinθ is used to find the difference in path lengths traveled by two sets of waves. Whether the resulting wave is constructive or deconstructive depends on the whether there is a whole or and a half difference in path lengths."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"Maxima and minima were confusing. double-slit interference was more difficult to understand."

"Definitely the picking the correct information to match the equation. All these symbols are confusing."

"The 'Train of Pain' is still a little confusing, just need to a little more with it."

"I understand the equations and the idea of the path lengths pretty well, but I might need some more practice using and applying them."

"I would benefit from homework examples that have to do with calculating the maxima and minima values to acquire a greater understanding of their relationship to the central bright spot."

"I pretty much understood everything, especially the basics. I might need some polishing of some concepts but that's it."

"Nothing at this time."

Explain the difference between "maxima" and "minima" in double-slit interference.

"The resulting constructive interference is the maxima, and the resulting destructive interference is the minima."

"A maxima is where it is brightest and a minima is where it is least bright."

"Maxima refers to the bright fringes while minima refers to the dark fringes."

Match the double-slit parameter with its symbol. (Only correct responses shown.)

Distance between slits: d [74%]
Any positive or negative whole number: m [74%]
Distance from slits to a projection screen: L [49%]
Wavelength of light passing through both slits: λ [83%]
Difference in paths for light passing through both slits: d·sinθ [51%]
Position along screen, as measured from the centerline: y [46%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [97%]
Path difference: integer number of wavelengths [100%]
Interference: constructive [97%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [89%]
Path difference: odd number of half wavelengths [94%]
Interference: destructive [94%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [97%]
Path difference: integer number of wavelengths [77%]
Interference: constructive [74%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Would like to review these last two diagrams in or after class."

"Are you going to go over this in class?" (Yes.)

"Will we be doing the double-slit experiment in lab?" (Yes.)

"Since the light that passes through the double slits is from a source that is side-by-side and in-phase with the same wavelength, won't the light passing through the two slits always be in phase?" (Well, yes, unless one wave has to travel a further distance than the other wave in order for them to meet at a receiver.)

"I'm not sure how to use the formula ∆l = dsinθ. In which case will the path difference be a whole wavelength or half a wavelength?" (Well, just calculate ∆l for a given θ direction, then see if it is equal to m·λ or (m + 1/2)·λ.)

"I think that in regards to Young's double-slit experiment, when two light paths interfere constructively they create a bright fringe, and when they interfere destructively they produce a dark fringe... is that correct?" (Yes.)

"I was a little confused whether the double-slit experiment only works when the light sources are side-by-side. If you have two separate sources of light that are constructive but that differ in distance does the double-slit experiment still work?" (Yes, but the sources must have exactly the same wavelength, and be in phase with each other. For visible light the most practical way to do this is to have a laser illuminate two side-by-side slits simultaneously.)

"I would benefit from some practice problems."

"Going to try my hardest to make it tomorrow."

Physics quiz archive: interference, electrostatics

Physics 205B Quiz 3, spring semester 2019
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz03b3Am



Sections 30882, 30883 results

0- 6 :	** [low = 3]
7-12 :	**
13-18 :	*********
19-24 :	***************** [mean = 21.5 +/- 6.0]
25-30 :	************ [high = 30]

Online reading assignment: double-slit interference

Physics 205B, spring semester 2019
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on double-slit interference.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"How the maxima and minima angles can give us constructive or destructive interference."

"Constructive interference leads to a bright fringe. Destructive interference leads to dark fringe. Intensity varies among the bright fringes; the central fringe has the greatest intensity."

"For two waves with in-phase sources and a distance of d apart from each other, we can approximate their path length difference by using the formula d·sinθ measured from the center line."

"When two waves are leaving from separate slits in phase they can be traveling parallel where θ = 0° and they would stay in phase. If the angle at which both waves are traveling is not zero then one wave is traveling a longer distance and thus can make the waves destructive interference. Constructive or destructive interference depends on how far apart the waves are from each other and the angle at which they are going toward the object."

"A detector can be used to detect the interference between two in phase sources that are side-by-side. The sources interfere at a detector that when moved side to side, create a path difference of the sources that can detect whether the sources interfere constructively or destructively. As the angle that the waves are moved changes, either by half a wavelength or a whole wavelength, the interference changes. "

"When light from two in-phase sources pass through slits, the two 'path lengths' of light from the slit to the point where they meet can relate in two important ways. If the lengths are equal or differ by a whole wavelength, constructive interference will occur when the two lightwaves meet and form a maxima. If the lengths differ by half of a wavelength, destructive interference will occur when the lightwaves meet and form a minima."

"Honestly I'm still kind of lost on this. I know we are looking for the difference in path length, but the equations are a bit difficult."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"I'm a little confused on what the variables are and how they relate to the pictures in the presentation."

"I don't understand the connection between maxima/minima angles and interference."

"I'm still not quite sure about what minima and maxima mean and how that related to constructive and destructive interference."

"I found the double-slit interference to be a little confusing where m is used as an integer used to describe how many wavelengths difference the waves are. It was confusing at first but after thinking it through and a little practice it made a lot more sense."

"I find it hard to understand the equations. Perhaps a tutorial in class may help."

"How do we know when to use each path length difference equation for the maximas and minimas?"

"I need practice applying the ∆l = d·sinθ equation. I also need to better understand the principle of a diffraction grating."

"Not confused much but would like to see examples."

"I am still a bit confused about how to apply the path length difference approximation in problem-solving. I feel like I understand the principles, different waves are interfering, but I do not understand why this is useful."

"Might be some confusion on putting all the pieces together."

"Not too much is super-confusing to me."

"I didn't really find anything very confusing I think I've got a pretty good understanding of the material. "

Explain the difference between "maxima" and "minima" in double-slit interference.

"'Maxima' refers to constructive interference and 'minima' refers to destructive interference, regarding double-slit interference of in-phase waves."

"Maxima is dark and minima is bright."

"It seems that maxima is a constructive interference and the minima is destructive."

"No idea--but I know calculus maximas and minimas."

Match the double-slit parameter with its symbol. (Only correct responses shown.)

Distance between slits: d [85%]
Any positive or negative whole number: m [85%]
Distance from slits to a projection screen: L [67%]
Wavelength of light passing through both slits: λ [92%]
Difference in paths for light passing through both slits: d·sinθ [54%]
Position along screen, as measured from the centerline: y [62%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [95%]
Path difference: integer number of wavelengths [87%]
Interference: constructive [97%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [74%]
Path difference: odd number of half wavelengths [82%]
Interference: destructive [90%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [90%]
Path difference: integer number of wavelengths [67%]
Interference: constructive [79%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"No question today, this all seems to make sense to me."

"How did I do on my ray tracings for the quiz?" (Have you checked your quiz scores online?)

"This was very helpful in making the path length differences and how the two wavelengths form the light and dark spots 'click' for me."

"Is there a way to mathematically check these examples above?" (Before every class, click on the "review previous reading assignment responses" link to see the correct answers for each reading assignment question.)

"I'd like to know how to do the interference from the path length differences." (You'll get to see this in lab.)

"Okay this might be dumb but I don't really understand what the double-slit interference is. I don't understand what this interference is supposed to represent." (It's a way of dividing a single beam of light into two (or more) separate beams of light, that can interfere with each other constructive (or destructively) in certain directions. Next week's lab is where we shoot a laser beam through a CD-RW disc, such that it passes through many adjacent tracks to separate into many separate beams of light that will interfere constructively (or destructively) at certain places on a screen.)

"Sometimes I get tripped up on the math, so the trigonometry confuses me a bit. I would love to see something drawn to scale where the parallel lines from the two slits end up creating a bright spot together." (We'll get to "act out" how two waves interfere constructively or destructively for double-slit interference.)

"Is there any way you can make the individual lab reports less time consuming and tedious, especially the procedure section? :(" (Although the procedure section can get tedious if you detail every step that you did in lab, there is a skill in summarizing that in a succinct manner (usually with diagrams) that I would like you to practice this semester. Shorter is better, but not too short.)

Physics quiz archive: interference, electrostatics

Physics 205B Quiz 3, spring semester 2018
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz03Ch4R



Sections 30882, 30883 results

0- 6 :
7-12 :	** [low = 9]
13-18 :	****
19-24 :	************ [mean = 23.3 +/- 4.9]
25-30 :	************** [high = 30]

Online reading assignment: double-slit interference

Physics 205B, spring semester 2018
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on double-slit interference.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"The general introduction to double-slit interference; more specifically the modified 'Train of Pain.'"

"We are able to find out if constructive or destructive interference occurs at a detector when two in-phase light waves are situated so that they are offset at an angle, which therefore also produces a difference in length. We can use an equation to find maxima/minima, angle, and length as they are related to each other."

"When comparing two waves that are both in phase, we're trying to figure out how much longer it takes for one wave to travel than the other. The path difference, how many wavelengths, etc."

"When considering path differences we can make the assumption that the detector is sufficiently far from the source of waves and that the two waves (d apart) travel along a parallel path. This makes it so that the location of the detector can be specified by a specific angle."

"Double-slit interference is basically a case in which waves from two side-by-side in phase sources interfere in both a constructive or destructive manner. In this lecture, source phases do not matter since we are looking at only in-phase sources, so our main focus of attention is looking at the path differences. The minima are where the paths interfere destructively, and the maxima are where the paths interfere constructively. There exists a trigonometric equation to determine how long a path is relative to another path as well."

"When comparing two waves that are both in phase, we're trying to figure out how much longer it takes for one wave to travel than the other. The path difference, how many wavelengths, etc."

"When we change the path of two waves, it affects the distance the waves have to travel to reach a destination. The equation delta ∆L = d·sinθ will tell if the interference is constructive (maxima) or deconstructive (minima)."

"The maxima and minima angles can give us constructive or destructive interference. This interference could be the product of waves having a path difference of a whole or half wavelength."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"Nothing was really confusing so far. I think the only thing harder to understand for me was the diagrams and the angle itself how that is found."

"How the altered distance of the two parallel waves effects their in/out of phase properties."

"I need more help on applying the ∆L = d·sinθ equation."

"I seemed to have understood this alright. Some lecture time would help me though."

"I'm confused about when a path difference would be destructive. My assumption is that the waves are constructive when the angle is at 0 degrees and destructive when the angle is larger or smaller than zero because these cases require that one path be shorter than the other."

"The path difference is really confusing to me. I think because it is harder to 'picture' in my head as I think it out."

"I don't understand the principle of a diffraction grating."

"Could you go over the equations?"

"I really don't find this presentation confusing. But how do we know and test which angles will be destructive and constructive?"

"I was pretty lost on finding the maxima and minima. I understood how you can manipulate delta l to be able to plug in wavelengths and m and then solve for an angle theta, but I don't know how this angle really comes into play in the big picture of it all."

"I really don't understand how path length differences are calculated."

"I didn't find anything too confusing in this lesson."

Explain the difference between "maxima" and "minima" in double-slit interference.

"'Maxima' is constructive interference and 'minima' is destructive interference."

"When two in-phase sources in a double-slit interfere at maxima this is constructive interference, and when they interfere at a minima there is destructive interference."

Match the double-slit parameter with its symbol. (Only correct responses shown.)

Distance between slits: d [74%]
Any positive or negative whole number: m [83%]
Distance from slits to a projection screen: L [55%]
Wavelength of light passing through both slits: λ [97%]
Difference in paths for light passing through both slits: d·sinθ [62%]
Position along screen, as measured from the centerline: y [55%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [100%]
Path difference: integer number of wavelengths [97%]
Interference: constructive [97%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [61%]
Path difference: odd number of half wavelengths [94%]
Interference: destructive [94%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [90%]
Path difference: integer number of wavelengths [74%]
Interference: constructive [84%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Review the above three diagrams from this assignment?"

"I could never go wrong with some more practice with the types of problems above, hopefully we have some in class :) ?"

"What is y? I put 'position along the screen as measured from the centerline.' Not sure I see what we are talking about."

"I am sorry I could not think of anything funny to write or ask this time, I will do better next time I promise.

Physics quiz question: double slit spacing

Physics 205B Quiz 3, spring semester 2016
Cuesta College, San Luis Obispo, CA

A red laser (wavelength 632 nm) illuminates two slits, producing a first maximum located at angle of 27° on a screen located 1.75 m away. The two slits are spaced __________ apart.
(A) 0.29 µm.
(B) 0.70 µm.
(C) 1.1 µm.
(D) 1.4 µm.

Correct answer (highlight to unhide): (D)

The first maxima angle θ for double-slit (and grating) interference is given by relation:

d·sinθ = m·λ,

where m = 1, such that:

d = λ/sinθ = (632×10^–9 nm)/sin(27°) = 1.39209...×10^–6 m,

or to two significant figures, 1.4 µm.

(Response (A) is λ·sinθ; response (B) is λ/(2·sinθ); and response (C) is λ·L.)

Sections 30882, 30883
Exam code: quiz03Ccf7
(A) : 0 students
(B) : 4 students
(C) : 4 students
(D) : 32 students

Success level: 80%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.11

Physics quiz archive: interference, electrostatics

Physics 205B Quiz 3, spring semester 2017
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz03d3St



Sections 30882, 30883 results

0- 6 :
7-12 :	* [low = 9]
13-18 :	*****************
19-24 :	******** [mean = 18.6 +/- 4.4]
25-30 :	** [high = 27]

Online reading assignment: diffraction, charges and materials

Physics 205B, spring semester 2017
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on diffraction and charges and materials.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"Diffraction is the spread of light from a single slit."

"Due to the diffraction minima equation, if there is a smaller slit opening, it would result in an increase of the spread of the diffracted waves and if you make the slit opening larger, it would result in decreasing the spread of the diffracted waves."

"Electrons in an insulator are constrained to their atoms, while a conductor has atoms that are more free to move around."

"When a neutral insulator (the electrons are pretty fixed in place) is placed near an object that has a charge there is a net attraction depending no matter what the charge is of the object. If a conductor (the electrons are way more free-moving) is placed near a charged object the electrons move away if it is negative or towards the object if it is positively charged."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"I don't understand why it is that the smaller slit gets a larger spread or vise versa."

"The mobility of electrons part was a bit confusing for me."

"I am having trouble understanding how a neutral insulator or conductor has always has a net attraction towards a charged object, regardless if it is negatively or positively charged.

Match the single slit parameter with its symbol. (Only correct responses shown.)

Width of a single slit: W [96%]
Any positive or negative non-zero whole number: m [76%]
Distance from the slit to a projection screen: L [84%]
Wavelength of light passing through the slit: λ [96%]
Direction, as measured from the centerline: θ [60%]
Position along screen, as measured from the centerline: y [48%]

A gas pump fire is inadvertently caused by the sudden discharge of an electrical spark. Describe when and how the woman became electrically charged.

"She became electrically charged after she got in and out of her car. This likely occurred as she adjusted her sweater because her hands were rubbing the electrically neutral fabric."

"What kind of sorcery is this?!? But I think she was able to transfer a change in electrons from clothes to spark a fire."

"When she is getting out of the car and as she slides across the seat she becomes charged."

"The lady became statically charged when she sat in her car. She could have de-charged by touching something metal to ground herself."

"This is one of my biggest fears, so I always make sure to touch something metal before I begin pumping gas

Electrically neutral polystyrene "packing peanuts" would be attracted to a cat that has __________ charge.

a positive.	* [1]
a negative.	* [1]
either a positive or a negative.	********************** [22]
zero (neutral).	[0]
(Unsure/lost/guessing/help!)	* [1]

An electrically neutral aluminum soda can would be attracted to a balloon that has __________ charge.

a positive.	[0]
a negative.	** [2]
either a positive or a negative.	*********************** [23]
zero (neutral).	[0]
(Unsure/lost/guessing/help!)	[0]

Electrically neutral polar molecules in a water stream would be attracted to a comb that has __________ charge.

a positive.	* [1]
a negative.	** [2]
either a positive or a negative.	********************* [21]
zero (neutral).	* [1]
(Unsure/lost/guessing/help!)	[0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Very cool to see different types of everyday things that people use or do and see physics out of it!"

"Practicing diffraction minima examples would be helpful."

"I did not feel as comfortable with the diffraction minima part of the blog. Why is the 'm' value equal to 1? Also, do minimas get categorized with a number like maximas do?" (Mathematically using m = 0 in the diffraction minima equation would give you a dark spot at θ = 0°, which is not what happens physically as the center is always bright, so we "disallow" using m = 0. Using m = 1 gives you the first minimas (dark spots) on either side of the central spot, which is effectively the "spread" of light on the screen. There are other dark (and faint light) spots farther out from the center, and so the locations of these (relatively unimportant) dark spots are given by higher values of m = 2, 3, 4, etc., until you get to θ = 90°.)

"I am slightly confused about using a hair in lab to diffract laser light--will it diffract light the same way as if it was going through a slit of the same size?" (Yes, due to Babinet's principle, light spreading out through a small opening will create the approximately same diffraction pattern as light wrapping around a small obstacle. If you think about light going through a small opening, it is curving around each side of the opening, causing light to spread out from the center. So when you look at light encountering a small obstacle, it will curve around each edge of the obstacle (and cross paths), effectively causing light to spread out from the center (ignoring most of the direct light that passes on either side of the obstacle that doesn't "wrap around" the edges of the obstacle).)

Online reading assignment: double-slit interference

Physics 205B, spring semester 2017
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on double-slit interference.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"I know the difference between maxima and minima."

"That the path length difference relation tells us where the maxima or minima will be."

"With the double-slit interference, the source phase differences don't matter, but that just their path differences do, we are wanting to know how much longer the wave from one source travels than the wave from the other source. I also understood that in a double-slit interference condition the constructive is maxima, and a condition that is destructive is minima."

"Double slit interference is two side-by-side in-phase sources. Phase differences don't matter with this and only the path matters. When calculating this we locate where these two sources interfere constructive (maxima) or destructively (minima)."

"A really small difference in distances can put waves in interference with each other; it is interesting how much of a difference it can be."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"I am not understanding the flow chart for the constructive and destructive conditions. How am I able to tell which pathway I am to choose for the condition I am given?"

"How to figure out the difference between the minima and maxima for double-slit interference."

"Path length differences. I'm just not fully understanding on how to find it."

"I don't really understand what double-slit interference is."

Explain the difference between "maxima" and "minima" in double-slit interference.

"Constructive interference is maxima and minima is destructive interference."

"The difference between the two is that the maxima is when there is a constructive interference or when the path difference is a multiple of the wavelength. A minima happens when there is a destructive interference or when the path difference is either an odd number of half wavelengths."

"No idea."

"I'm trying to understand it."

"Maxima and minima is the minimum and maximum of wavelength?"

Match the double-slit parameter with its symbol. (Only correct responses shown.)

Distance between slits: d [77%]
Any positive or negative whole number: m [77%]
Distance from slits to a projection screen: L [41%]
Wavelength of light passing through both slits: λ [100%]
Difference in paths for light passing through both slits: d·sinθ [50%]
Position along screen, as measured from the centerline: y [46%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [95%]
Path difference: integer number of wavelengths [91%]
Interference: constructive [91%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [59%]
Path difference: odd number of half wavelengths [86%]
Interference: destructive [77%]

Identify the characteristics of the sources, path difference, and interference type. (Only correct responses shown.)

Sources: in phase [73%]
Path difference: integer number of wavelengths [82%]
Interference: constructive [68%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Can we discuss the difference between maxima and minima in double-slit interference?

"Do we call it maxima/minima only when we're talking about interfering waves?" (Well, yes, but this works for both interfering sound waves (loud/quiet regions) or interfering light waves (bright/dark regions).)

"Petition for more long weekends!"

"Did you ride any emus over the long weekend?" (No, but Mrs. P-dog and I went snowshoeing up in the mountains.)