I mentioned earlier of an article on the Davisson-Germer's experiment as part of the commemoration of 100 anniversary of Quantum Mechanics (QM). This is an article describing a bit more of the celebration and the importance of QM. Hint: without QM, none of your modern electronics (computers, smartphones, etc.) will work.
Zz.
As we continue to celebrate 100 years of Quantum Physics, this is a fun account of the famous Davisson-Germer experiment that was the first to demonstrate the wave-like nature of electrons.
It's interesting that, at the end of the article, it was pointed out that this experiment did not originally was set out to seek the experimental evidence for the wave-like nature of electrons. They were intended to do something else, and then learned about something, and adapted it later. This is not really that unusual. The first thing that popped into my head was the discovery of the cosmic microwave background (CMB) by Wilson and Penzias. They certainly were not looking for the CMB with their microwave antenna. It was a serendipitous discovery. In fact, one can even say that the discovery of superconductivity also came out of an experiment that was not designed to look for it, because no one knew at that time that such a thing could exist.
One could say that this is another one of those "Who Ordered That" scenario.
Zz.
Rhett Allain posted this article on Wired on the 5 physics equation that "everyone" should know. They are, in the order that was presented:
You can read the article to see what he has to say about each. I'm going to show this article to my students and see what they think, or maybe ask the how many of these do they think we will encounter in the course.
Zz.
This is similar to my earlier query regarding the sequence of topics that are introduced. My earlier post was the order of introducing the concept of energy and the concept of momentum. In this post, it is the issue of the sequence of introducing the double slit interference ahead of the single-slit diffraction.
This sequence is done in Knight's text "Physics for Scientists and Engineers". I don't follow that sequence because I prefer to introduce the single-slit diffraction first, show the diffraction pattern, and then introduce the double slit. The fact that the double slit pattern has interference pattern inside a single-slit diffraction envelope is easier to explain after the students already know about the single-slit diffraction.
What do you think? How did you teach this topic, or how did you learn this topic?
Zz.
The US National Science Foundation (NSF) will be livestreaming the total Solar Eclipse of 2024. Here is the blurb from them:
Don't just watch the eclipse — explore it. On April 8, the U.S. National Science Foundation and the NSF National Solar Observatory are hosting an educational livestream all about the science of the sun.
The livestream is a free resource that educators can use in their classrooms to share the excitement of science.
You'll hear from scientists about the unique experiments happening during the eclipse. As we count down to the moment of totality, you'll learn about:
- The different layers of the sun, from the core to the corona.
- The world's largest, most advanced solar telescope.
- How massive solar eruptions generate space weather.
It all happens on YouTube on April 8 starting around 11 a.m. PDT/noon MDT/1 p.m. CDT/2 p.m. EDT.
In my algebra-based General Physics courses, I get many Biology/Pre-med/Life Science majors, so of course many of the examples that I choose tend to be related to those areas. When we cover traveling waves and Doppler effect, I dive into medical diagnostics to show a few of the applications of Doppler effect in that area.
Interestingly enough, in Doppler Ultrasound, the color scheme that they use tend to be a bit confusing with what we use in physics. In the Doppler effect, when the source of a wave, or the source that is reflecting the wave, is moving away from the observer, the wavelength will be longer than the original wave. We popularly say that the wave has been "redshifted". This is because in the visible spectrum, the longest wavelength is toward the red color.
Conversely, if the object is moving toward the observer, then the wavelength will be shortened, and thus, "blueshifted", since blue (or violet) is the shortest wavelength in the visible spectrum.
But this is not the color scheme adopted in the field of Doppler Ultrasound, as represented in this video:
It seems that if the flow is toward the transducer, it is given the red color while if the flow is going away from the transducer, it is given a blue color.
Obviously, this is not a source of confusion for people in that field since they don't normally encounter those color-shifted lexicon, but for students who are studying this topic for the very first time, this takes a bit of an effort to make sure they do not become confused with the contradicting color scheme. The first time I used the Doppler ultrasound example was, unfortunately, right after I discussed an example from astronomy where I indicated that most of the light from the galaxies are redshifted and thus, a strong evidence that the universe is expanding since those galaxies are moving away from us. You can imagine that the students who were paying attention got a bit confused because the blood flowing away from the transducer is now being labeled with blue color instead of red.
Does anyone know why this field adopts this color scheme?
Zz.
Please read the article carefully before you freak out. Hint: look at the date.
Zz.
This is a rather fun article in this week's Nature. It reveals some of the fascinating origin of words used in Physics and how they may not match the more common usage of the word.
All of us in physics (and in science) know of this, where we may use the same words that are used in everyday language, but they have very different meanings in physics. Unfortunately, for many people outside of physics, this can lead to a lot of confusion or misuse if they do not investigate or understand the meanings of those words as used in the context of physics. The word "spin" comes to mind when talking about the quantum spin of elementary particles.
Z.
Previous posts:
My favorite web applications - Part 1
My favorite web applications - Part 2
My favorite web applications - Part 3
My favorite web applications - Part 4
My favorite web applications - Part 5
My favorite web application - Part 6
My favorite web application - Part 7
This is another one of my favorite web application because it has a ability to assign random values to various parameters in the problem.
This is a simulation of a motional emf in the form of a rail gun. It actually is a straight-forward application of magnetic force acting on a straight current. One may also solve this using Faraday's law, but it is not as straight-forward to solve because the magnetic flux (or rather, the area) does not change uniformly since the rod is accelerating.
What I also like about this simulation is that one can also tie in with what the students learned in Physics 1, i.e. they may verify their answer using kinematics, since we know the rod's mass, and it starts moving from rest. Knowing how far it travels and a good estimate of the time of travel gives us the value of the acceleration, and thus, the force acting on the rod. This should match with the magnetic force.
Zz.
A while back, I wrote an article on how to impress upon the students of the need have units in most of the numbers that they write in physics. I gave them a recipe for a banana bread, but I left out all the units of measure. It was the students themselves who noticed what was wrong with the recipe, so in the process, I managed to convey to them that (i) without units, these numbers are meaningless and (ii) this is not just something in physics (or science) but rather something common that we encounter and take for granted.
Over the Summer, I did the same thing but I showed them a recipe for my often-requested Chewy Oatmeal Cranberry cookies. Same reaction. But the difference happened at the end of the arduous and intense 8-week summer session. On the 2nd to last day of the class (last day was the final exam), after we did our review, I showed them again the cookie recipe and asked them if they remembered why I was showing them the recipe. All of them did.
I then whipped out a container that had the very same cookies, from the recipe, that I had baked the day before. Oh yeah, they were pleasantly surprised! We basically came full circle, and had a lovely time the last 15 minutes of class time as we sat around chatting and munching on the cookies. Even the coffee machine was nearby and a few of us got some coffee to go along with the cookies.
It was a wonderful end to the class, in my opinion. I am considering this Fall semester if I want to do that again. I just might, if I can find the time.
Zz.
This is a nice news article that provides a basic summary of the applications of physics in healthcare and medicine. It's another one of those where if someone thinks physics only deals with esoteric and useless ideas, show him/her this. I've mentioned many examples of similar medical/health/etc. applications and concepts that came directly from physics, such as this one.
As someone who often teaches general physics to life science/premed/bio/kinesiology major, this is definitely another useful evidence to get them to realize that the physics class they are taking has a direct relevance to their area of study.
Zz.
It's one of the reasons why I groan at popular media's reporting of science.
This article is reporting on a paper that proposes a possibility of finding evidence of large-scale symmetry breaking from the data ".. in current and upcoming surveys such as those undertaken by Dark Energy Spectroscopic Instrument, the Euclid satellite, and the Vera C. Rubin Observatory.... ". Yet, the article is trumpeting the "Incredible new evidence...." as if it has been found. This is similar to accepting speculation as the truth.
Over-selling and over-hyping science does no one any good, other than making it a click-bait.
Z.
Many of us knew that it would be a significant instrument. We just didn't know that in its early days, it would make this many discoveries.
In case you were asleep for most of the past 12 months, here is an article that will highlight some of the groundbreaking discoveries made by the JWST. It will not be hard to guess that there will be more earth-shattering (universe-shattering?) discoveries to be made in the next 12 months.
Zz.
