Tag Archives: Light

To Infinity Table and Beyond

Light, it’s properties, and the ways it can be manipulated are as fascinating as they are beautiful. It can be bent, slowed down, absorbed, and reflected. It turns out that the study of optics looks into all of these different interactions. But what happens when you want to mix the science of optics with a bit of real-world fun? You get an infinity table!

Infinity tables are named as such due to the illusion that the lights go on forever down into the depths of the table. But how can that be?

Infinity Table

To answer this, you not only need to know how the table was made, but also what optical properties those materials have. The three materials that makes these tables unique are LED lights, a normal mirror, and a two way mirror. The LEDs of course provide the visually pleasing light source. The normal mirror on the bottom of the table allows for the light to be completed reflected back up. And finally, the two way mirror allows for half of the light to escape the box of the table, and the other half to be reflected back down.

Because half of the light can escape through the two way mirror, with each bounce, half of the light is lost from the box. This is how the light appears to grow dimmer as you look down further into the apparent depths of the table.

Infinity Table 1

These tables are not the easiest to make at home, however it is not impossible. A simple home goods store may have all of the supplies needed. Just be sure to have adult help and supervision if you are to attempt this, given that glass is involved.

Written By: Mimi Garai

Fiber Optics: Continuing the Light Discussion

Fiber optics allow for the transmission of information, like the internet and cable TV. They carry information between two places using entirely light-based technology. In a cable, there can be as little as two fibers, or as many as several hundreds. Each fiber is about as thick as a human hair. But how does it work?

fiber optics

For the clearest example, a laser beam can be sent down the fiber. The laser is always one color of light that travels coherently. Coherence is when waves of light line up to be in phase. Two different colors of light can never be coherent because they have different wavelengths.

fiber optics 1

The light from a laser (Light Amplified by Stimulated Emission of Radiation) will also always travel in a straight line. So why can it bend around and through a fiber or stream of water?

fiber optics light

The fibers being used are made of glass, plastic, or a combination of the two. These all have a higher index of refraction than the air, causing the light to bend from one medium to the next. If the angle that the light is being bent is less than 42˚, then the light will bounce backwards as if it hit a mirror. This is called total internal reflection.

fiber optics light 1

The light waves are guided through the optical fibers due to this phenomenon of light bouncing back and forth down the cable. This allows the light information from the beginning to be able to make it all the way to the other side without losing much energy along the way.

 

Written by: Mimi Garai

Light: Just Flip It and Look You Will See

It is no surprise that we experience and use scientific phenomenons every day. But, did you know that our eyes do that too? At camp, we have a science experiment that demonstrates how our eyes take in light. This hole in the wall is a great model for an eye. Your eye has a few major components: cornea, lens, iris, pupil, retina, and macula, to name a few. For our purposes, let us focus on the iris and pupil. The pupil in an eye is basically just a hole. The iris is a muscle that can expand and contract to change the size of the pupil. The purpose of the pupil is to allow light to enter your eye.

light

light eyeLight, on Earth’s scale, travels in straight lines. So how does any of that light ever make it into your eyes for you to see the world around you? The key is reflection. Light bounces off of objects, and if it bounces just right, that information will make it all the way to you. However, the only light you will ever see are the rays that make it all the way through those tiny holes.

So why is the image that is formed upside down? Due to light traveling in straight lines, when the light that bounces off of someone’s head, that same information makes it through the hole. Any other reflection of light will slam into the wall, unable to pass along the data. Same thing goes for light bouncing off of someone’s feet. Because the light is entering through the small hole, it must intersect and thus the image is inverted. However, we don’t see the world upside down. Our brains have adapted to this phenomenon, and flips the images automatically! Our brains are amazing!

light more

Written By: Mimi Garai

Look up and Constellations

A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere. They typically represent animals, mythological people, gods or creatures. There are 88 modern constellations, but just because those are the ones that are recognized doesn’t mean that one you make up is less valid.

The stars that constellations are comprised of are not necessarily stars that are near each other. So how do they appear that way? It’s all about perspective.

constellations

Take for example, The Big Dipper, an asterism in Ursa Major. An asterism is a smaller part of a constellation, usually with more noticeable stars. The Big Dipper is composed of seven bright stars: Alkaid, Mizar, Alioth, Megrez, Phecda, Merak, and Dubhe. Together, they appear to be in the shape of a spoon (use your imagination). However, they are all different distances away from Earth as well as from each other. Their distances from Earth respectively are roughly: 104 ly, 78 ly, 82.5 ly, 80.5 ly, 83 ly, 79.5 ly, and 123.6 ly.  

constellations gif

But if you simply change your perspective, or location from which you’re looking at them, then the picture changes! Unfortunately, since we are all on Earth, our perspective can not move enough to make a big difference.

Written by: Mimi Garai

Gravitational Lensing

gravityMost of us have experienced using a lens in some way, whether it was using glasses, cameras, or our favorite, telescopes. A lens is a piece of glass or other transparent substance with curved sides for concentrating or dispersing light rays. They have the ability to bend light! Did you know that gravity can bend light in the same way? We call this gravitational lensing; when a large massive object, like a blackhole or galaxy, passes in front of our view of a distant light source and a distant galaxy. It bends the distant light in different ways, sometimes creating two or more images or creating an Einstein ring, a complete ring of the image.

 

gravity 1

The glass shape at the bottom of the stem of a wine glass, and looking straight through the glass has almost exactly the same optical properties as a massive galaxy or blackhole!

When you pass the glass over a light source or picture, it distorts the light into an Einstein Ring. This is one way Astronomers know about dark matter! According to Einstein’s theory of general relativity, the presence of matter (energy density) can curve spacetime, and the path of a light ray will be deflected as a result.

gravity 2

Written by: Mimi Garai

Watch what happens: LED in Liquid Nitrogen

It wouldn’t be surprising if nitrogen was your favorite elements. N2 is the most common molecule found in our atmosphere, making up roughly 78% of it. But here at camp, we have a different reason for why it is one of our favorite things to have around. We have a ton of liquid Nitrogen on camp and love using it to freeze things. We wanted to see what would happen when an LED (Light Emitting Diode) was submerged in the -321˚F liquid.

It turns out that something pretty cool happens… it changes colors! But why would cooling it down, taking energy away from the LED allow the color to change in a more energetic direction?

LED

To answer that we need to know how LEDs work. They are two-lead semiconductor light sources that emit light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes on a positive or negative band within the device, releasing energy in the form of photons.

LED 1

When an atom is at rest it’s electrons are at the lowest energy state possible. With LEDs, an electron is shot in, hits another electron which increases its energy, hopping up to the opposite band. When it starts to rest enough, it falls, giving off a photon (light particle). The bigger the hop in energy state, the greater the fall will be, and therefore the more energetic the photon will be.

LED 3

The electrons start off with a bit of thermal energy, but when submerged in the liquid Nitrogen some of the thermal energy is removed. When the thermal energy is removed it allows the distance between the bands (the band gap) to physically increase which in turn will increase the fall of the electron, increasing the frequency of light!

Written by: Mimi Garai

The Cleaning Secret of Bleach


If you’ve ever done laundry, you know that bleach stains dark clothes and brightens light ones, but why does it do that? Well, the answer is all down to chemistry.

Bleach 1

Inside the dyes we use in clothes, food, etc., there are chemicals called chromophores. These chromophores reflect a specific wavelength of light, causing them to appear a certain color, like purple in the case of the water in our video.

Bleach

However, when bleach is added to the equation, it goes through a process called oxidation, releasing oxygen molecules. This oxygen reacts with the chromophores, breaking up the chemical bonds between them. With their bonds broken, the chromophores reflect less color, an altered color, or even a wavelength of light outside the visible spectrum depending on the type of dye in use. The reduced or invisible color reflection is just seen by our eyes as white, making light colors look lighter, and the stronger dyes like the dark purple water shift to another color, appearing as a bleach stain on our dark clothes.

 

More Fluorescent Bubbles!

Can’t get enough of bubbles? Here at AstroCamp we love playing with them too! This is a great DIY that you should definitely try at home. All you will need to make fluorescent bubbles is a blacklight, bowl, dish soap, ink from a highlighter, a little water, and a bubble wand. Then let the fun begin!

Fluorescent

But what are you really seeing? We know that can have a funny way of working sometimes, and fluorescence is one of those times. Fluorescence is a property that only some materials have. It is the property of absorbing light of a short wavelength and high energy, and then emitting it at a longer wavelength and lower energy. This is a type of luminescence which is the emission of light due to a chemical reaction, electrical stimulation, or stress on crystals.

For the case of the fluorescent bubbles, the violet and ultraviolet light interacts with the highlighter fluid. Don’t worry, it is a low energy ultraviolet that will not harm you. Ultraviolet light is too high of an energy for humans to see. The highlighter fluid absorbs that high energy light, and then emits its own lower energy, visible light, which we can see as the impressive glow! Try it out with different colors to experiment which colors of highlighter fluid works best.

fluorescent flower

But where else is ultraviolet found? Did you know that the sun is the main source of ultraviolet light? There are actually some animals on Earth, like reindeer and butterflies that can see in the ultraviolet spectrum, and some flowers that have patterns in their petals that can only be seen in the the ultraviolet. So the next time you are outside on a bright sunshiny day, get your fluorescent bubble solution out and try to see the world through a new filter.

fluorescent daisy

How it works: Pyrex Glass vs. Vegetable Oil

There isn’t much that comes to mind when we try to compare the similarities of pyrex glass and vegetable oil. No, we are not baking or cooking, we are simply doing an awesome at-home science experiment. It turns out that these two things have something very fundamentally in common: they have the same index of refraction of light!

Light interacts with most things around it. It can travel through things, bounce off of them, and even bend. Reflections are those images that we see in the mirror, it is when light hits a different medium and then bounces off of it. Refraction is when light hits a different medium and instead of completely bouncing off, some light will bounce off of the medium and some of it will bend. To learn more about how we can bend light, click here.

Different mediums can bend light in different ways due to how much they are able to slow it down, referred to as its index of refraction. Water, for instance has an index of refraction of 1.33. Pyrex and vegetable oil both have refractive indexes of 1.47 and air is at about 1.00. If we combine substances with different refractive indexes, we can see some interesting effects.

If you place a small pyrex beaker full of air into a larger pyrex beaker full of vegetable oil you will be able to see the smaller beaker due to the different indexes of refraction of air and pyrex. However, if you let the smaller beaker fill with the oil, it will seemingly disappear because pyrex and vegetable oil have basically the same index of refraction.

Hiding from Thermal Vision

Thermal cameras operate by looking at objects in a different band of light called infrared, which is the way heat transmits. Ordinarily, you could see a person from behind a wall or other solid object by looking in the infrared, as their heat still passes through that object somewhat, like with the garbage bag (DO NOT TRY THAT AT HOME).

 

In the case of plexiglass and glass, however, infrared light is not able to pass through, resulting in a blank spot where Jacob’s head and hand used to be. You can even see it with Jacob’s glasses, as they are cooler than most of his face in the infrared.

 

We actually use this property of plexiglass here at AstroCamp for several solar-powered devices. The inside of our solar ovens are black so they absorb visible light, heating up, and have a plexiglass door covering them so that heat can’t escape. We also use this for a solar water heating system where visible light strikes a black metal tube, which heats up and conducts heat well, then that heat is trapped by a plexiglass covering. Our IR camera is a great source of learning, but it’s also just a lot of fun.

WELCOME TO OUR ASTROCAMP BLOG

We would like to thank you for visiting our blog. AstroCamp is a hands-on physical science program with an emphasis on astronomy and space exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and astronomical happenings. This blog has been created by our staff who have at least a Bachelors Degree in Physics or Astronomy, however it is not uncommon for them to have a Masters Degree or PhD. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science, space and astronomy information. Feel free to leave comments, questions, or share our blog with others. Please visit www.astrocampschool.org for additional information. Happy Reading!

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