Field Trip Explainers

Reflections on life at Exploratorium

Circuit Inspiration

by Julie C.

Explainers spend a fair amount of time in the Tinkering Studio playing with Circuit Boards. We connect motors to batteries; compare series and parallel circuits; and experiment with types of switches. Visitors join us throughout the day to create their own circuits.

But, what is an electric circuit?

An electric circuit is “a complete conducting loop from the positive terminal to the negative terminal [of a battery], with both the battery and the light bulb [or other component] being part of the loop.” *

blog circuits circuit

But not all circuits are so simple… Read the rest of this entry »

Explainer Recipes

by Julie C.

Allison has collected the culinary wisdom of Explainers. From herbivores to carnivores and complicated to simple, here is the result. Click through for all of our recipes or add your own in the comments!

Recipe_Robert

 

Robert, Ham Sandwich:
Ham
Bread (not necessary)

Read the rest of this entry »

Pianos and Proprioception

by Julie C.

A few weeks ago we experimented with our sense of proprioception. Proprioception is the sense of where our bodies are in space and how much force we need to use to move them. If your sense of proprioception is impaired you may talk too loudly, press a pencil hard onto paper, or grasp things too forcefully. Going through a growth spurt often temporarily impairs one’s proprioception, which is why adolescents tend to knock into things.

We tested our own senses of proprioception with blind drawing. We sat in the West Gallery and took five minutes to draw the exhibits around us. The only rule was no looking at our paper while we did it. A few people drew the same exhibit. Can you tell which one it is?

BlindDrawing02-10

 

Read the rest of this entry »

Camera, Camera on the wall, who’s the hottest of them all?

by nlcarlson

If you have ever stood next to another human being, then you probably felt some body heat radiating from her. What you might not realize is that everything emits radiation: you, your dog, your chair. Everything! (see this article: http://discovermagazine.com/2007/jun/life-is-rad).

Explainers play in the infrared camera with ice and hot water. Photo courtesy of Sylvia Algire*

Now you are probably asking yourself “Am I the same as a chair?”. While only you can truly answer that question, for the purposes of this blog post, the answer is “no”. The key difference is that you and your chair radiate different amounts of energy.

Physicists model objects that radiate heat as black bodies. A black body is an idealized object that absorbs all energy (specifically, electromagnetic radiation) that hits it. A black body will emit radiation in a way that is solely determined by its temperature. The emitted radiation is described by Planck’s Law. Note: only click on the link if you can handle lots of maths.

Thus, if we could measure the radiation emitted by a black body, we could determine the object’s temperature. Luckily, the world we live in has such measuring devices: infrared cameras!

An infrared camera measures the infrared radiation emitted by objects and then calculates the apparent temperature of each object. The objects are then colored based on their temperatures (see attached photos for some examples).

However, real objects are not black bodies because they only absorb part of the energy that hits them while the rest of the energy is reflected. The percentage of energy that an object emits back is defined as the object’s emissivity. Therefore, if the emissivity of an object is known, the camera can correctly estimate the temperature of the object and produce an amazing picture.

Photo courtesy of Sylvia Algire*

In short, infrared cameras give us an opportunity to see into a completely different world. Now that you’re done reading, go play in front of an infrared camera with hot water, dry ice, and your own body.

To learn more about the nitty gritty details of infrared cameras, look up Thermography. Thermography is the field dedicated to infrared imaging including measuring radiation and estimating/measuring emissivities. Thermographers (I totally made up this word) develop fancy algorithms and methods for calibrating infrared cameras. If you are interested in reading more about thermography, check out these links:

  • http://www.testosites.de/export/sites/default/thermalimaging/es_AR/local_downloads/testo_thermalimager_pocketguide.pdf
  • http://oce.jpl.nasa.gov/practices/at9.pdf
  • Short-wave infrared camera picture of mock-dead Explainers. Photo courtesy of Jenny Situ*

    *All pictures were taken with the infrared camera or short-wave infrared camera at the Exploratorium (www.exploratorium.edu) during a Field Trip Explainer training session.

    ** Apologies to any physicists reading this post if I simplified things too much!

    Image | January 29, 2014

    by Julie C.

    20140128AllisonBlogPost

    This is a comic that Allison drew . It’s a funny comic and a true story!   The broken piano was turned into the exhibit, Piano Strobe. A strobe light is directed at the exposed strings of the piano. If the strobe flashes at the same speed that a string is vibrating, the string will appear […]

    November 20, 2013

    Seeing Polarized Light

    by nlcarlson

    “Once you see it, you can’t unsee it”

    Earlier this fall, I conversed with Julie about what superpower we would choose. She mentioned that she and Rob were interested in learning how to see different types of light. I immediately grew excited because this seemed like an attainable superpower. I decided to focus on seeing polarized light.

    During my search, I even found a website that listed seeing polarized light as a useless superpower (http://io9.com/5601591/developing-useless-superpowers-101-how-to-detect-polarized-light). My search ended with Haidinger’s Brush (http://en.wikipedia.org/wiki/Haidinger%27s_brush), the manifestation of how humans see polarized light.

    Haidinger’s brush is a visual phenomenon seen in polarized light that looks like a yellow bowtie with a blue bowtie perpendicular to it (see Figure 1). People do not usually see it naturally, but most can train themselves to detect it. The easiest way to see the brush is on the white screen of an LCD monitor (for example, you could use the computer that you reading this blog post on). Be warned though, once you train yourself to see it, you will probably see it on every future computer that you look at.

    Open source image of Haidinger’s brush from Wikipedia

    After this initial research, I quickly coerced my study group into investigating this phenomenon. We initially tried staring at blank Safari tabs on iPads. Hartley was the first to reach success, but Raquel and I needed some extra help. We decided to go on a search for polarizing filters in the museum.

    During our trip to the shop with Kate, we fortuitously ran into the museum’s neuroscientist, Richard Brown. He immediately knew what we were talking about and agreed to help us out. He gave us some tips on ways to train our eyes, and he also mentioned that some light-eyed people might never be able to see the brush (take that recessive genes).

    Richard’s main tip was to try rotating the iPad smoothly while looking at it from a distance. We achieved this by using a turntable provided by Kate and standing on the Explainer Hub table. Soon Raquel, Kate, and I were able to see a rotating yellow brush. Hartley claimed that he could also see the blue bowtie as well, but this claim has yet to be verified.

    We decided to share our newfound powers with the other Explainers during our Friday meeting. Although I had to miss that training, Raquel and Hartley reported back that some Explainers were able to see the brush. Unfortunately, Julie was not one of them; she’ll have to find her own superpower.

    Overall, I am ecstatic that I have succeeded in turning myself into a superhero. The next challenge is training myself to see Haidinger’s brush in the sky. And like every superhero, I’ve already obtained a supervillian: the rain in San Francisco is deliberately thwarting my attempts to see the brush in the sky.

    November 13, 2013

    Happy Halloween from the Explainers!!!

    by salamandersal

    DSC_0099DSC_0104 DSC_0109 DSC_0113 DSC_0118 DSC_0121 DSC_0122 DSC_0131 DSC_0148 DSC_0152 DSC_0153 DSC_0157 DSC_0158 DSC_0162 DSC_0155 DSC_0128

    Video | October 30, 2013

    Cloudy With a Chance of Joy

    by klstirr

    We have been pretty excited about clouds ever since we began plotting our cloud demo several years ago, but our energy around clouds has been supercharged by Gavin Pretor-Pinney and his Cloud Appreciation Society. One of my favorite quotes from his TED talk posted above echoes something that is one of my goals for visitors (and for myself) in many of our demos and interactions at the Exploratorium: as Gavin says, “You don’t need to rush off away from the familiar, across the world, to be surprised—you just need to step outside, pay attention to whats so commonplace, so everyday, so mundane, that everybody else misses it.”

    His talk, and the Cloud Appreciation Society as a whole, remind us that we are not separate from our atmosphere—”we don’t live beneath the sky, we live within it,” and that “cloudspotting legitimizes doing nothing…and reminds us that just being here and letting your imagination lift from the concerns…of just being in the present is good for you—its good for the way you feel, its good for your ideas, its good for your creativity, [and] its good for your soul.”

    So, look up at the clouds & find joy in being here in the world!

    October 20, 2013

    Bloody Eyes!

    by Julie C.

    One of our most popular demos at the Exploratorium is the cow eyeball dissection.

    cow eye

    The inside of a cow eye, looking through the pupil.

    Before we cut open the eye, we often ask for predictions about what we’ll find inside. Will it be hard or soft? Full or empty? Fluid or solid? Will it be bloody or clear or melanin-colored? We get all sorts of interesting predictions which flow into more questions about eyes.

    The other day, I got a question from an interested visitor: “Does a horned toad have blood inside its eyes? Because horned toads can shoot blood from their eyes to scare predators.” I didn’t know the answer and we discussed some possibilities. We thought about tear ducts, blood within the eye, and how fluid moves in the eye.

    Here’s the answer: Horned Toads (actually lizards) shoot blood from their eyes by “restricting the blood flow leaving the head, thereby increasing blood pressure and rupturing tiny blood vessels around the eyelids” (Wikipedia). Some bugs and snakes also autohaemorrhage to protect themselves from predators. There have been cases of humans “crying blood”. Human haemolacria isn’t a defense reaction but is thought to be a symptom of another disease, an injury, or tumor.

    I do not recommend trying to cry blood, rupturing your tiny blood vessels, etc! Instead, check out the exhibit Blood Vessels of the Eye in the Exploratorium’s Central Gallery or try this version of the exhibit at home. And if you’re interested in cow eyeball dissection, here are how-to instructions!

    July 1, 2013

    Super moon, super tide?

    by Julie C.

    During the summer months when we aren’t Field Trip Explaining; we’re exploring!

    Last week, I headed over to the beach the morning after the supermoon or perigee-syzygy of the Earth-Moon-Sun system! Isn’t that a great term? Perigee means that the moon is closest to earth in its elliptical route. Syzygy of the Earth-Moon-Sun system means that those bodies are aligned, ie: a full or new moon.

    My thought was that the tide would also be exaggerated. I headed over to Land’s End around 7am to check (here’s a tide chart for areas around San Francisco.) While the tide was very low, but it was only a little lower than last month’s low tide caused by the normal full moon…Which is good news because there were all sorts of amazing creatures to see exposed on the beach!


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