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More Sodium

Posted on by Brian Garthwaite
You’d think it would be more complicated inside.

Here, our more modern sodium light sources, using a clever design that enabled a reduction from the minimum 35W to as little as 18W in 1977. Cool, yeah?

Unfortunately, Philips finally bowed out of the low pressure sodium lamp game in 2019, mean we’ve got these dinosaurs running for as long as we can scour spare lamps online. Once the supply’s gone, it’s gone.

Pure sodium!

Hey, look! Sodium metal! Highly reactive, so it’s inside with a mixture of 99% neon and 1% argon, neither of which deigns to react with, well, anything. That’s why, when it starts up, we see a purplish glow from the noble gases before tube reaches 260°C and vaporizes the sodium. After that, it’s an intense monochromatic yellow-orange that’s hard to look at.

Low Pressure Sodium

Posted on by Brian Garthwaite
Burnt-out low pressure sodium lamp
Toast.

Remember the old, aggressively-yellow street lighting that pre-dated LEDs, ceramic metal halide, and high pressure sodium? Turns out it’s very useful for physics, as the two strong emission lines near 589nm are handy for various experiments.

The lamps themselves are fairly tough, and the ballasts that operate them even more so. But, eventually, they burn out.

General Electric ceased production on these lamps back in 1972. So, no, sorry, replacements are not readily available.

Part 2

Posted on by Brian Garthwaite
Second part of the Math 101 final exam, from November 16, 1948
“End of Test”

It’s part two of our Math 101 algebra final!

Someone really likes to underline for emphasis. They did not want the students to miss that the quadratic formula would be essential for solving 3x2 – 5x + 7 = 0.

Of course, nothing’s as charming as the wiggly, fancily-underlined “End of Test” text. Right?

Part 1

Posted on by Brian Garthwaite
Ditto of Math 101 final exam, part 1, from November 15, 1948
Ditto!

Astronomy, here and elsewhere often under the Physics umbrella, was once part of the Mathematics department at Bucknell. Occasionally, we’ll stumble across some old files in the Observatory that have been yellowing gracefully for decades. Like this two-part final exam from Math 101. Algebra!

Of note for context: this old exam – November 15th, 1948 – waited patiently in a filing cabinet at the current Observatory, built in 1963. In all likelihood, it sat in a folder in the old Observatory for thirteen years, transferred to Tustin Gym for a time, and then quietly continued to be forgotten in a new building until some tech decided to clean the place up a bit.

Who doesn’t love finding curiosities in purple ditto ink?

Stamped

Posted on by Brian Garthwaite
Lead brick, painted yellow, stamped by Nuclear Associates of Carle Place, NY.
It’s big, heavy, and boldly colored.

Lead bricks are useful things. This one – still bearing the stamp of Nuclear Associates, of Carle Place, NY – has had its fair share of scuffs and dents. (Lead’s soft stuff, you know.) These days it functions as a handy doorstop and a hands-on tool for explaining the density of matter.

Denser than water, than aluminum, than a nickel-iron meteorite. (All easy samples to acquire for demonstration.) Less dense than osmium; about half as much. (Not on hand, unfortunately.) Definitely less dense than the core of our Sun, by an order of magnitude-plus.

Also no handy samples of stellar core plasma on hand.

Do Not Touch

Posted on by Brian Garthwaite
Orange warning label reads "CAUTION Touching or handling delicate optical components will destroy them"
If they could have added a klaxon, they would have.

There are times when you want your warnings to be relatively subtle. Visible, readily noted by anyone paying attention. And then there are the ones demanding you take notice.

Do you know what’s in here? (Not specifically.) Do you think you should open and check. (Not particularly.) Are you curious? (Yes, very much so.)

When there’s an obnoxiously bright orange label warning that fingers will destroy the contents, it’s easy to recall that there are loads of other toys around here which are a wee bit less delicate.

Yo-yos also come in bright orange.

Bespoke Breadboard

Posted on by Brian Garthwaite
Long piece of aluminum, in process of machining mounting holes.
So many.

Need a thing, but can’t get it in the right size, right shape, right odd set of dimensions? That’s one reason to keep a workshop in the basement. If we can possibly make it, we’ll certainly try.

Pictured: a custom optics breadboard, for a very specific apparatus, with many, many drilled, tapped, and cleaned 1/4″-20 mounting holes. It’s big, and shiny, and has a bright future ahead!

Probably with lasers or something. Lots of lasers around here.

Crookes Radiometer

Posted on by Brian Garthwaite
Spinning Crookes radiometer on a sunny windowsill.
Sometimes a little lens flare is fun.

Here in the basement, we have all sorts of curiosities. (Hence this strange blog.) Among them, a Crookes radiometer happily spinning in the sunshine. It’s a delight on these crisp, clear, wintry mornings.

The short version: inside a partial vacuum, little black-and-white vanes sit atop a low-friction pivot. When heated, typically by sunlight (but a flashlight will do), it begins to spin, as if propelled by an invisible thrust from the black sides of the vanes. We’ve been told it’s a process of thermal transpiration that makes this happen, but no matter what, it’s oddly hypnotic.