Our friends stopped by with a simple apparatus to demonstrate the diamagnetic properties of bismuth metal. Diamagnetism is a extremely weak magnetic effect — generally orders of magnitude weaker than everyday permanent magnets, which exhibit ferromagnetism. However it is also an extremely interesting effect because diamagnetic materials are repelled by magnetic fields. This is different than the case with ferromagnets, where one pole of a magnet repels another — rather, the entire material is (weakly) repelled by any magnetic pole.
Now, how might one observe such a weak effect? One way is to build a magnetic levitation rig, but the field configurations there are a little less obvious. With a simple but sensitive balance, we can see the repulsion directly. The balance above has a long wooden beam, a central pivot on two blocks of plastic, and a couple of coins on the far end for counterbalance.
At the business end of the scale, there is a cylinder of bismuth metal about 1 cm in diameter, held in place by a rubber band. We also have a larger rectangular block, which is our test magnet, made of grade N50 NdFeB and painted black. And finally, the Lego Astronaut Twins are here helping out as a scale and position reference.
Moving the block magnet beneath the bismuth, we can see what happens in an animated GIF:
After the balance settles, the resting position of the end with the bismuth is considerably higher. With some calibration in terms of weights and/or positions, one could even measure the exerted force with some precision.
A slight improvement to this apparatus would be to reverse the roles of the bismuth and the block magnet. That is, to affix the magnet to the arm of the balance, and to slide the bismuth beneath it instead. You could then use a nearby block of aluminum to damp the motion of the beam through magnetic (eddy current) damping. Many commercial balance-beam type scales already use magnetic damping so that they settle down to their final values faster.
For each of the last two years, we’ve released sets of “Download and Print” cards for Valentine’s day. The 2013 set had six equation-heavy cards, and the 2014 set was a set of six symbol-heavy cards. This year, we’re releasing six new cards, bringing the collection up to a total of 18 cards. This year’s new cards feature love, hearts, and arrows (but no bows or cupids):
For when your love is complex, but not whatsoever imaginary.
For that moment when you want to express that not only is the first derivative of your love positive, but so is the second.
(Just in case there was a danger of none of these being sufficiently cheesy.)
Not sure how we missed this one in last year’s set of symbols. Alternate caption: “You light up my life.”
And what better way to say “I love you,” than with the gift of a math problem?
You can download the full set here, which includes all 18 designs from the three years (a 765 kB .PDF document).
As usual, print them out on (or otherwise affix to) card stock, and [some steps omitted] enjoy the resulting lifelong romance.
Update: New cards have been released! Please check out the 2019 set, which contains all 42 cards from 2013 through 2019.
The SPARK (Science Play and Research Kit) Competition is requesting submissions for what they are calling “Reimagining the Chemistry Set of the 21st Century.”
To be clear, we’re interested in science beyond chemistry. We borrow this term to capture the spirit and magic of what the classic chemistry set spawned in the 1940s – 60s. We’re looking for ideas that can engage kids as young as 8 and inspire people who are 88. We’re looking for ideas that encourage kids to explore, create, build and question. We’re looking for ideas that honor kids’ curiosity about how things work.
We’ve delved into that spirit with our posts on Vintage Chemistry Manuals and Vintage Chemistry Sets. We also see it in our community in groups like Public Lab, with projects like Thermal Photography. It is exciting to see this contest trying to promote that spark of curiosity. Submissions are due in January, and we’re looking forward to seeing the winners when they’re announced in February. In the meantime, we would like to hear what you want to see in science kits for the future.
The stent pictured above is an example of an Open Stent from NDC, makers of nitinol materials and devices, particularly for medical applications. In their introduction to the project, they write:
The first problem that we encounter when developing useful and practical educational resources for stent design is that every design we might want to use as an example is proprietary! That leaves us without much to talk about… So to solve this problem, the first step was to create a design to use as an example. The Open Stent is designed to be completely generic, but also realistic, and relatively easy to modify and extend to be useful for whatever purpose a designer intends.
In addition to publishing their draft of Open Stent Design, which they call “a practical guide and resource for design and analysis of a generic Nitinol stent,” NDC has provided extensive calculation tools and CAD files as well, to help others evaluate and create derivatives of the design.
The project is a fascinating open source hardware use case, where creating an open design provides a platform for education and discussion where none existed before. It’s also very exciting to recognize this as an early example of open source hardware in the field of medical devices— one of the places where open hardware can potentially make a very big difference in the world.
Remember those vintage chemistry sets that we opened up the other day? We left out one of the coolest things that came along with them: A thick stack of fantastic manuals, instructions, posters, and charts. Let’s take a look through them!
Continue reading Vintage Chemistry Manuals
A good friend recently presented us with his estate sale find: two 1960’s era vintage chemistry sets. One set is big, white, and mysterious, the other is smaller but showier. Let’s take a look at what’s inside!
Continue reading Vintage Chemistry Sets
Our collaborator Sylvia went on the Katie Couric show yesterday. She showed off the WaterColorBot and did a couple of science demonstrations with Katie. Her video segments are here and here. Fantastic job, Sylvia!
Fern Canyon is a lush little feature of Prairie Creek Redwoods State Park— a tiny winding canyon whose dripping walls are lined with soft ferns and vibrant mosses.
The park is located very northwest corner of California, nestled against Redwood National Park. The two parks are managed together, as part of the “Redwood National and State Parks.” It’s a substantial six hour drive north from San Francisco or Silicon Valley, but as you will see, it’s unique, and arguably worth the trip.
Continue reading Field Trips: Fern Canyon
Kitty’s Morning Tea: Kinetic Theory of Matter for Kids, by Christine Liu, is a remarkably charming book and physics lesson for young children. It’s a short twelve-pages about tea, molecules, and kinetic energy that you can read (in its entirety) above, in a digital edition released by the author. We love seeing science-themed educational materials for youngsters— and this is no exception.
Christine and friends are running an (already funded) campaign on Kickstarter to print the book and get it into the hands of children, and you can get your own printed copy as one of the rewards. It’s also available in a Kindle edition, free for the short remaining duration of their campaign.