Tag: light

A Layman’s Guide to Photonic Crystals

The first time I heard the word “Photonic Crystal” in a seminar, I was stumped. So I decided to read about it, understand and then write about it to make it explain better to me, and you of course. Even though it is a whole graduate level class to explain, it does not hurt to quickly look at how Photonic crystals work. I have not taken the relevant graduate class. However, after reading this amazing answer on Quora, and from a range of other literature out there, I was able to make some good sense out of it. My idea was that at least by doing a little reading you get to throw around a fancy word like “photonic crystal”. Moreover, if someone decides to test you on what it means, you even explain it to them. These kind of examinations, where it is incumbent upon you to perform well, happen all the time, everywhere. That’s why it is important to learn. And well, then there’s that whole argument of expanding your mind to exercise your creative muscle by reading and listening carefully to things and people that are out of what you do.

Featured image credit: Flickr, Steven & Courtney Johnson & Horwitz (Picture)

Continue reading A Layman’s Guide to Photonic Crystals

Estimating the Distance of a Lightning Strike

By Anupum Pant

Everyone who’s studied basic science at school knows that light travels much much faster than sound. Light can travel about 300,000 km in a single second. Sound, in the same time would cover about 0.3 km. That’s a huge difference.

Considering that, it is fairly easy to calculate how far a lightning strike happens by measuring the time it takes the sound to reach you after you see the lightning. In that case, taking into account the enormous speed of light, you assume that the light instantly reaches you and you just count the seconds it takes for the sound to be heard at the place you are.

Then multiplying the seconds with 0.3 would give you, in kilometres, how far it happened – an estimation of, course.

So, if there isn’t a mess of lightning strikes happening somewhere, which usually isn’t the case, and if you can clearly tell which sound came from which lightning strike, which you can’t in most cases, you can actually estimate the distance of a strike very easily.

If you think that’s great. You might be interested in:
How to estimate the temperature.
and How to estimate the time to sunset.

A Scientist’s Way of Making Super-Strong iPhone Cases

By Anupum Pant

Bulk Metallic Glasses (BMGs) A.K.A Amorphous metals, give you the goodness of both metals and glasses. They literally are glasses made out of metal. Unlike the most crystalline metals, BMGs are made by cooling certain liquid metals very quickly to lock the disordered glassy structure in place. They aren’t crystalline like your everyday metals and instead have a structure like that of glasses – disordered.

Some of these BMGs have amazing properties. Like super high hardness, about 3 times the hardness of steel is one of the most alluring properties they have.

They’ve been around since the 60s, and mass producing them has always been tough. Until now, BMGs were never used for something as ordinary as a smartphone case. But the recent innovation in manufacturing coming from a Materials scientist at Yale will probably soon bring to the market these new iPhone covers that’d be 50 times harder than plastic, or 10 times harder than Aluminium, and almost three times the hardness of steel.

[Video] What Travels Faster Than Light

By Anupum Pant

Like always, another one of those awesome Vsauce videos where Michael explains how darkness and scissor intersections can travel faster than light and still not go against any physics laws. So much to learn! Let me just say nothing today.

P.S there’s a mention of the Dunning Kruger effect and the story of Mr. Mc Arthur Wheeler I covered some time back on the blog.

Seeing Sound

You can skip everything under this subheading

Note: In the past, I’ve been requested by my readers to keep the articles on AweSci short. It made sense. Since I write one article everyday, for readers, it definitely is easier to read and digest a smaller article, day in and day out. Thanks to the rate at which short attention span is being nurtured by the internet, not all have the appetite to take in bigger pieces everyday.

I see it this way – doing a very little thing everyday religiously, compounds. It makes a huge difference in your life. Even devoting 2 minutes a day for a single thing makes big changes over time. Here, I’m doing more than an hour everyday! If you read these daily, you are devoting around 10 minutes a day to learn something. You’ll do great in life!

At the same time, smaller articles of about 300-500 words are good for me too. By sticking to smaller ones, I can accomplish my own goal of learning and writing about one new thing everyday, by doing less. Also, composing smaller articles doesn’t take a lot of time which allows me to take care of the primary daily activities.

However, today, a reader asked me about the decreasing length of my articles. It’s so good to know that readers actually care about these things. Nevertheless, as explained above, there’s nothing wrong in it, but it did make me think about what was causing it? Well, I’ve been busy with so much stuff for the past few days, I don’t have partners for the blog and it’s tough doing it alone. Still, with all the travelling and full day outings in a 40 degree sun for the past few days, I managed at least one article a day. Pat on the back to me for being able to do that.

Anyway, the point is that articles don’t have to be long. For the question my faithful reader asked me, I needed to write this to explain it to him. He deserves a good explanation for being faithful reader to my little blog. If I learn something and sleep a little bit smarter than the last day, I’ve accomplished my goal for the day. That way, the purpose of you reading this is served. That way, the purpose of the blog is served.

What do you say, long or short? Or, you are always welcome if you want to contribute on this blog. We have hundreds of people who’d come by daily to read your article!

Background

In the past, we’ve seen how geniuses at MIT have figured out a way to capture the beam of light on video, and have replayed it moving in slow motion. In simple words, moving light was captured on camera. Something which the human eye had never seen before was shown moving with the help of technique. But, then there are other invisible things too. Like sound!

Watching sound

Watching the iTunes visualization go, isn’t equivalent to watching sound. Visualizations and waveforms are merely a digital depictions of sound.

While listening to sounds can be too easy, seeing it with your eyes isn’t natural. For that, there is camera trick that can be used to see the actual sound waves travelling in the air. In fact, with this technique, any disturbance in the air can be seen which otherwise, would be totally invisible to the naked eye. It let’s you see sound!

The camera technique has a fairly confusing name. It’s called Schlieren flow visualization. But that shouldn’t confuse you because in simple words, with this technique it is possible to capture on film, the disturbances that are caused by things moving in the air. For example, the invisible disturbances that are caused in the air (a transparent medium) when someone claps can be made visible by using the technique – Schlieren flow visualization.

Here is how it works

Photograph of a wind tunnel model using a schlieren system along with a schematic explaining the operation of the system

If I write it in words, I’ll only confuse you more. So, here is an NPR video that explains the mechanism very accurately. Otherwise, there’s always this NASA page for it.

Amazingly, like the video shows, it can be used to see the heat coming off the human body. Now, I can definitely think of some creative applications for that.

Yes, Light Can Push Physical Objects

By Anupum Pant

Tim is a 71-year-old eccentric who has been collecting interesting toys for 50 years now. Today he has a collection of around 250,000 absurd toys in suitcases, labeled and stacked in a room from the floor to the ceiling. He shows them off in a Youtube channel regularly. I almost never miss any of his toys. Usually most the toys he displays amaze you, but do not blow off your mind. The last one did.

Before this, I had not known that light can push or move a physical object. So, I decided to investigate a bit.

The Extraordinary Toy

In his last video, he showed off a beautiful glass bulb mounted on a wooden stand, that he says has been made by some German company. The bulb has a very good vacuüm (not complete vacuüm, just enough to not create unnecessary drag for the vanes) and encloses a fan-like structure that starts rotating when a bright light is switched on near it. Some people call it the light mill – like the wind mill moves with the wind, this one moves when photons hit it. If give enough time, the mill can accelerate to really good speeds (at thousands of rounds per minute). Watch the video below. [Video]

Theories on how a radiometer really works

The device, a special kind of radiometer, was invented around 140 years back in the year 1873, by Victorian experimenter Sir William Crookes to measure the radiant energy of heat or light. It has four vanes mounted at the edge of four stiff wires to make a fan, each of which has a black side and a silvered side. All of this is enclosed in a bulb which is evacuated enough to not cause drag due to air. In complete vacuüm the vanes move in an opposite direction, but that experiment is really difficult to recreate!

  1. When light is turned on, the fan moves in a way that makes it look as if light is pushing away the black colored side. The theory of photons pushing the black side was accepted initially. But soon a problem was seen with the theory. If light is absorbed at the blackened side and reflected at the silvered side, the fan should be moving in the opposite direction.
  2. Then came in the other explanation which explained that the heated black side due to absorbed radiation rarefied the air near the black side and hence caused the gas to rush in and push that side. The greater the heat, the more this back side would get pushed and it would spin faster. Later even this theory was proved to be wrong. But, Britannica, till date decides to go with this explanation – to some extent this theory goes in the right direction, you will see why…
  3. One more theory claimed that the heat evaporated the impurities on the black side, whose force made it spin.

How the radiometer really works?

The correct explanation was given by a  prominent Anglo-Irish innovator, Osbourne Reynolds. He explained it by mentioning a porous plate, where the air inside the holes would flow from the colder sides to the warmer side (obviously) and make the vanes spin in the opposite direction. He called it “Thermal Transpiration” – makes sense and is easy to understand. But the vanes here are not porous. So…

He said that “Thermal Transpiration” in the vanes takes place at the edge of the vanes and not the faces. Think of edges as small pores, he said.

Due to a temperature gradient formed, the air starts moving along the surface from colder to the warmer side through the edges. The net pressure difference around the vane is created which pushes it in a direction that is away from warmer air and towards the colder air – makes sense for the apparatus.

This is the reason, if it is cooled, it moves in the opposite direction.

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15 Craziest Ways to Charge Your Phone [Part 1]

By Anupum Pant

What was considered a remarkable method some years back, today, using solar cells to charge your phone has gone too main stream. How about doing it with a flamethrower, or moon light maybe? Brace yourselves up for an unusually long and interesting compendium of some the most craziest things you could use to charge your phone. And of course, I thank science for bringing these things into the world.

Here, I’ve compiled a few crazy ways to charge your phone. Feel free to contribute any others you know and point out ignorance in the comments section below.

Note: The absurd methods I’ve collected here may set your phone on fire, or worse. So, please do not try them at home. If you do, and succeed in melting your phone, do not blame me for it. Or rather, read whatever you can find about it, before experimenting.

1. Moon Light

What if photovoltaic cells were so efficient that they could draw electricity from the moon-light all night? Well, here you go.
A German architect named André Broessel worked on a project for 3 years to put together a novel process of drawing solar energy that would be far more efficient than the existing ones. In the end, he came out with this perfectly spherical glass ball filled with water, which can use up whatever minimum light it receives to create electricity. So, on a cloudy day or even at night (using light from sun reflected by the moon), with this set up on your terrace you’ll be making electricity 24X7. Moreover, you don’t have to worry about the sun or moon moving in the sky. It comes with a tracking system which adjusts itself to capture the light.
It is basically a super-refined version of one of those solar death rays I talked about a few days back.

Your phone is small; this is something which could make whole skyscrapers go off-grid. So, go and give it away on Indie GoGo whatever little you can contribute to the project.

2. Hand Cranked

ku-xlarge

With the amazing moon light capture device for the future, now let us move on to this hand cranked variant of a mobile power bank, you can buy right now. For everyday use, this backup battery pack comes with a hand turbine power generator that will keep you all charged up all the time. It contains a rechargeable 2000 mAh lithium battery for power which can be cranked up for about a minute to create 4 minutes of battery life out of thin air. If you were expecting free energy, in the end, it is important to know that with this device, to bring your phone from completely dead to 100% battery would require nearly an effort equivalent to a full-body workout.
Also, I found a cheaper variant, which works on a similar principle but isn’t documented well on the internet. It got “India talking” for obvious reasons (costs only $7). They call it the RotoCharger.
If you are looking for an easier way, read on.

3. Lightning

Yes, the same thing that Raijin (雷神) drops on earth 100 times every seconds,  is 3 miles long and carries a current of 10,000 Amps at 100 million Volts, was used to charge a Nokia phone. Last year, scientists from the University of Southampton teamed up with Nokia to try and harness the energy of a lightning bolt to charge a phone. They succeeded in charging a Nokia Lumia 925 with a 200,000 volt lightning bolt, created in the laboratory.

Here is a YouTube video posted by Nokia’s official YouTube channel demonstrating the same:

4. Wind/Air

IfanBlog

In a recent development, researchers at the University of Texas at Arlington have developed a micro-windmill made up of a nickel alloy. It is so small that you could put 10 of them could on a grain of rice. According to them, in the future, hundreds of these tiny windmills could end up in the housing of your smart phones and power them using wind energy.

Earlier, undergrads from Nirma University of Ahmedabad in India had developed an eco-friendly headgear that used a little fan for harnessing wind energy. As it also uses solar energy, at just $22, it is indeed a great device for charging your phone on the move.

Talking about devices that can harness wind energy on the move, the iFan is one ingenious device that comes to mind. It can be mounted on a bicycle or can be held outside a car window to charge your iPhone.

Lung Power: Talking about air, there is this clever gadget that transforms the air from your lungs into energy to charge your phone. Created by Inventor Joco Paulo Lammoglia, from Rio de Janeiro, Brazil, AIRE mask can harnesses the wind power created by breathing and converts it into electricity to run anything from your iPod to your mobile.

5. Body Heat

body heat phone charger

Working on the same principle as the flashlight without batteries, a jacket developed by Stephen Beeby, Professor of Electronic Systems at the University of Southampton, uses thermoelectricity to power your phone. According to the professor, you have to sleep for quite some time to find a fully charged phone:

Eight hours in the sleeping bag, roughly speaking, will provide 24 minutes of talk time and 11 hours of standby time. That’s assuming the inside of the sleeping bag is 37 degrees – human body temperature.

6. Sound

soundcharge tee

In theory, talking to your can generate energy to charge a phone. Although to win a substantial amount of battery life from this prototype, you’ll have to scream at the top of your voice. According the lead researcher, Sang-Woo Kim of Sungkyunkwan University’s nanotechnology institute who invented it, it requires 100 decibels to generate 50 milli-volts of electricity. That’s enough to give a Smartphone battery a little support, is still far from what a normal wall plug charger could give you. The researchers are really confident about taking this technology to the next level and making it viable for practical use.

Another one: GotWind’s Sound Charge t-shirt converts sound into electricity. A person wearing this can charge a device battery while thrashing around in the mosh pit. A textbook sized panel of Piezoelectric film in the front acts like a microphone. It absorbs sound waves and converts them into electricity through the compression of interlaced quartz crystals. This electricity is then fed into an external power bank. [Video]

7. Shake

There was a time when kinetic wrist watches were the fad. Today, how cool would it be if you could shake up your phone for an extra boost?
So, Researchers at Virginia Tech tried to make a charger that draws energy from a piezoelectric material and could convert vibrations into energy. They say, when it is done, simple taps on the phone screen or keyboard would produce enough energy to deal with emergencies.

But, long before the researchers announced this, the world had seen nPower PEG. Apparently, it is the world’s 1st human-powered charger for hand-held electronics. It gives you access to backup battery power even when you’re away from home by using the energy you generate while walking, running, or biking to charge your smart phone, music player, GPS, or other devices.

Ah! I’ve written too much for the day. Remember to check back next week for the 2nd part of this post. 

Moving Light Captured on Camera

By Anupum Pant

The speed of light

In vacuüm, light travels 299,792,458 meters in a single second. In other words, in a single second it travels 186,000 miles. To establish a  perspective, if I could move that fast, I would circumnavigate the world in 0.13 seconds. A hypothetical jet plane would take more than 2 days to do the same. In short, it is fast. It is the fastest – Nothing beats light.

If you try to record moving light on a home camera, you’d fail miserably. That is because normally they can roll only about 30 to 60 frames per second. In fact, you’d not even be able to capture a fast-moving ball without motion blur, forget recording moving light. To record fast things you need fast cameras that can roll several thousands of frames every second.

In the past, high-speed-cameras, rolling film at thousands of frames per second have been able to record bullets moving in slow motion, bubbles bursting, people getting punched and what not! MythBusters use such cameras for almost every experiment they do.

But light travels a million times faster than bullets. Till the year 2011, to capture moving light on film was considered an impossible feat; and then, a team from MIT media lab invented this.

A 1,000,000,000,000 FPS camera

A camera that can record at a speed equivalent to a theoretical one-trillion-FPS camera was invented by a team at MIT media labs in the year 2011. This camera can record light moving through space, in slow motion! To look at what it can do, you’ll have to watch the video below. In the video, the researcher explains its mechanism in detail.

It is theoretically impossible to craft a mechanical device that can roll film at such extremely high speeds. To tackle this physical limit, these geniuses invented a whole setup containing several cameras sensors that work together to make this feat possible.

Note: In reality, the camera doesn’t record the footage of a trillionth of a second. It is a composite video of lines of different pulses of a laser recorded and stitched together. The time it takes to compile enough data for the video, is more than what it takes the light to travel from one end to another.

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Darkness Is Good For You

By Anupum Pant

It is astounding how the tiniest things can affect your life greatly. Who would have thought that sleeping with lights on can change you into a completely different person, over time?

Sleeping with lights on, or simply not getting enough exposure to darkness can have long-lasting effects. Darkness is good for you.

Melatonin – The Darkness Hormone

Melatonin is a hormone found in all living creatures from the most basic ones to humans. Melatonin is produced in the pineal gland (a part of the brain), by the retina, lens and GI tract. Production of melatonin is influenced by the information received from the retina about the daily pattern of light and darkness. It is primarily secreted when the information of “darkness” is obtained by the gland.

Its Effects

Its levels vary in a daily cycle. In humans, it plays a role in the regulation of several biological functions. Three of its functions we are interested in here are – its effect on out mood, performance and aging process.

Aging, behavior and memory effects:
According to one study, in mice that were aged artificially, Melatonin had immense anti-aging effects. In a similar study, the combined effect of physical exercise and increase in of Melatonin concentration led to improvements in behavior, learning and memory.

Studies on humans have also produced results on similar lines. The hormone’s effect on mood, performance, memory and visual sensitivity were assessed among 14 healthy men in a study carried out at MIT. It was found that externally administered Melatonin had a significant but short acting sedative-like effect on humans. In terms of mood, it had a calming effect.

Anti-Cancer effects:
Melatonin causes cancer cells to self-destruct. The hormone also boosts your production of substances that make your immune system stronger. As a result, your system gets better at identifying and attacking mutated cells that lead to bad cancer.

Other effects:
Melatonin’s effect is not just limited to that. It plays a great role in decreasing Heart Diseases, Headaches, Diabetes and Osteoporosis too. And more…

Improving your Melatonin production

  • Avoid screen time during the last few hours of your day before going to bed.
  • Avoid using any sort of night-light or bed-side lamp. Sleep in complete darkness.
  • Avoid waking up abruptly due to loud alarms or bright light. Use a crescendo for alarms.
  • Sleep away from your phone.
  • Maintain a set light and dark, wake and sleep rhythm.
  • Most important of all, to optimize the production of this hormone, you need exposure to bright sunlight during the day. Unlike what just-the-headline suggests, it is important to note that you are not doing yourself any good by lying in darkness all the time. There has to be a continuous rhythm of light and darkness.
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The Underwater Optical Man-hole

By Anupum Pant

Agreed, sometimes, when you find yourself being interrogated in a room covered with one-way mirrors, you can’t see the people who are observing you; Instead, you see yourself in the mirrors. Otherwise, If you can see something, it seems normal to assume that the thing can see you too.

A trout’s window to the outside world is something similar to what a person in the interrogation room experiences. However, unlike the person, a fish can actually see things that are out of the water, but the view is very limited.

The Snell’s Window

When a fish looks up from water, it sees only a circular window of light, from under the water surface. Everything that lies outside of this circle is darker. This darker area of vision is replaced by the reflection of the sea/lake bed (where there is no source of light to illuminate it). This effect isn’t due to any limitations of a fish’s eye. In fact, even human divers see only a circle of light when they are under water. This circle is called the Snell’s Window or the optical man-hole.

Irrespective of the fish’s visual acuity, some physical properties of water and air get together and have a great effects on what a fish can see. It sees a circle with diameter calculated by the Snell’s equation.
In short, the window is about 2.3 times as wide as the fish’s depth. So, a fish can see more if it goes deeper. At a depth of 1 meter, it can clearly see things on a circle that is 2.3 m wide on the surface of water.

So, even if you can see a fish in water, it will be foolish to assume that the fish can see you too. Some times it can’t. It looks something like this from under water:

In Wikipedia’s words:

Snell’s window is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees.

Why does it happen?

It happens due to a simple optical phenomenon called the total internal reflection.
The physics behind this phenomenon can be read here. [Read here]

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There Is No Pink

By Anupum Pant

As we’ve seen before in a talk by David Eagleman, that there is nothing like colors really. They are simply electromagnetic waves with varying wavelengths. Colors are perceptions created by our brains that give us an evolutionary advantage to differentiate things easily. Without colors it would have been really difficult for us to spot fruits on trees. Of course that is just one of the millions of examples of how colors help us.

Perception kept aside for a while, we actually do know that there is a spectrum of visible light as we see it – ranges from violet to red. We see this spectrum on rainbows and thin films. Each of these colors on the spectrum is a wave (and particle) that has a particular frequency.
Mysteriously, the universal symbol of love, the color pink, is absent in this spectrum. There is no specific frequency for the color pink. There is no pink. Still we see it. So, what is pink, really? If it isn’t in the spectrum, why do we see it?

Why do we see pink?

Single type cone alone: We detect colors through these things called cones that are present at the back of our eye. There are 3 types of cones – let us call them red, blue and green. So, if an object absorbs all the white (sun) light and sends just the red color [waves] towards your eyes, red cones get activated and your brain tells you, you are seeing the color red. Similarly, green or blue cones get activated when the respective green or blue waves come towards your eye and then you are able to see the colors green or blue.

2 of them together: For other colors, things can get a bit complicated. To see pure yellow, both red and green cones have to get activated. Similarly, when green plus blue cones get activated, you see cyan, and blue plus red cones let you see the color magenta.

But cone aren’t switches that go either one or zero. They are like sliders. For instance, to see the violet color, your blue cones get fully active, while the red cones are activated only to a certain extent. As a result, your brain says, violet! That is 2 types of cones working together.

3 of them together: Now let us see how three of them work together. The color white activates all the 3 type of cones fully. Black activates none. And so on…

Pink does something similar as it uses three types of cones. To see pink, all three types of cones have to work together.  When red cones get fully active and the other two are only partially activated, we see the color pink.

So, even if objects don’t reflect magenta, yellow or pink (or several other RGB combinations like that), our cones can send mixed signals to our brains and the brain in turn creates these colors for us. In reality, they don’t exist.

[Read more]

What is pink really?

Henry Reich of minute physics, in his video explains this by referring to pink as white minus green. So, according to them, the color pink is actually minus green.  In short, absence of green color is nothing but pink. I’ve attached the video below:

Miniature Sealed Self-Sustaining Ecosystem

By Anupum Pant
  1. 53 years ago, David Latimer (80) from Surrey planted an indoor Spiderwort in a huge glass globular bottle. He has watered it just once, in the year 1972. Since then, this self-sustaining ecosystem, has been sealed away from the outside world for around 40 years. In spite of being sealed away like that, the plant has grown very well in its own miniature ecosystem [Picture]. The only regular external energy it has received has been in the form of light. [more about this self-sustaining ecosystem and how it works]
  2. The EcoSphere or the Original EcoSphere takes it to the next level by introducing a shrimp in a similar setting. Like David Latimer’s bottle, this is also a self-sustaining ecosystem consisting of algae, bacteria and shrimp. The company that sells these things says that the shrimps would last for just around 10 years. Although, they also claim of 25-year-old spheres with living shrimps.
    10 years is little as compared to the ecosystem discussed in the first point. But we are talking about a pet living in a completely sealed space for 10 years, without demanding food, change of water or an appointment with the vet. For these little creatures it is probably a safe haven away from the dirty oil slicked oceans and predators; or probably just a prison.

These little biospheres are a far simpler and smaller versions of our big worlds. We are like the shrimp and the trees, our algae. This diagram explains in a simple way, how these artificial, extremely simplified versions of Earth work – [Diagram]

The shrimp and algae biospheres were discovered by two scientists, the late Dr. Joe Hanson and the late Dr. Clair Folsome. Later, NASA became interested in these systems. There got interested because:

  1. This tiny model of the Earth could add information to NASA’s Mission to Planet Earth program for studying Earth’s biosphere.
  2. It could help NASA’s research on human life support systems directed toward the construction of space stations for exploring our solar system.

Make it for yourself: Make magazine published a detailed DIY guide on how to create these living biospheres at home. [Link]
Carl Sagan’s Review of these biospheres: The World Arrived in The Mail.

Random Foliage Fact:

The world’s smallest park is located in the median strip of SW Naito Parkway, approaching esplanade along the Willamette River near SW Taylor Street in downtown Portland, Oregon, United States. Mill Ends Park, a 2 ft is a circular park, has held a place in the Guinness book of Records since 1971. It isn’t a park you can send your children to. – [Wikipedia]

A Flashlight That Uses Body Heat Instead of Batteries

By Anupum Pant

I talked about a light that utilizes the power of gravity to light up a few days back. This flashlight is a bit similar in a way that, it also doesn’t need any batteries. But the underlying mechanism it uses, is completely different.

The winner of this year’s Google Science Fair, in the age group of 15-16, was a 15-year-old girl from Canada, Ann Makosinski. In her project she created a flashlight that, instead of batteries, uses our body heat to light up. She calls it “Hollow Flashlight”

The flashlight uses 4 Peltier tiles to convert the temperature difference (between body and room temperatures) into energy. One side of the tiles is heated by our body heat and the other side is at room temperature. This temperature difference creates electricity using the Thermoelectric effect. The tiles used for this light need a minimum of 5 degree difference of temperature to work.

Peltier Tiles

Peltier tiles utilize thermoelectric effect to convert temperature difference into electricity. When there is a enough temperature difference, charge carriers move from hot area to the colder area. This separation of charges builds up a potential difference across the height of the tile. This potential difference can be used up for various things. In this case, it was used to light up LEDs.

Advantages: The amount of potential difference produced depends on the material. Peltier tiles are great because they are compact and they do not use any moving parts. Elimination of any moving parts eliminates wear and tear. They last long and do not need a lot of maintainance. However, their efficiency is not so great. So, they are used only where long life is essential.
The Voyager space probe and other deep space probes, where long life is of prime importance, use Thermoelectric generators (another image). The heat there is produced by a radioactive isotope. Implanted pacemakers which require long life also use it as a source of energy. All of them work utilizing the same effect – thermoelectric effect. The eco-fan, a wood stove fan, also uses the same effect in a very creative way.

Thermoelectric Generators have a very interesting history.

Gravity Light – A Light With No Running Costs

By Anupum Pant

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A $5 lamp that lights up using gravity can be used without electricity or batteries, over and over again with no running costs. Impressive enough? There is more.

A British company, after working for 4 years on this project, with an aim to replace kerosene lamps, started an internet fundraising campaign on Indiegogo and successfully raised about 7 times more than what they had aimed for – aimed for raising a fund of $55,000 and ended up raising $399,590. They had invented the Gravity Light.

Gravity light uses the force of gravity to light up – a free, completely reliable and totally unlimited source of energy. For it to start, the user is supposed to lift up a hanging weight of about 10 kg. And there! As the bag full of dirt, stones or sand starts coming down slowly, it lights up an LED light. The weight keeps coming down for about 30 minutes and then it has to be raised again. It generated a very minuscule amount of electricity and manages to give out a much brighter light than a kerosene lamp.

The energy generated from it can also be used to charge batteries, charge phones, run a radios etc, with attached accessories.

Interestingly, the company has plans to develop various other gravity powered solutions. So, in the future, we might probably see a way to reach the internet without batteries or electricity.

Other interesting lighting ideas:

[Gravia lamp] [Water + Bleach lamp] [Algae + CO2 lamp]

 

Bricks Which Are Lighter Than Air

by Anupum Pant

What would smoke look and feel like, if you could solidify it?

Aerogels

Although, first made in 1931, Aerogels are relatively newer materials and a tremendous amount of research is being done on them everyday. Lightest solids ever, Aerogels weighing about seven times lesser than air have been made. Their extreme properties have given a fascinating field of interest to students and scientists. [Read the last paragraph]

How are they made?
Aerogels, also known as solid smoke or frozen smoke are extremely light materials. They are made by a process called sol-gel process which involves removing all the moisture from a specially made gel (Hypercritical Drying). Although the procedure may sound simple, there is a lot of technology involved in making them. Moreover, practically usable Aerogels which can endure moist conditions and high stress conditions are much more challenging to make. Also, it is very expensive to make them. [They can be made at home – with costly equipment of course]

Why is it so light? 
The whole lot of porosity left inside due to drying of the gel is what makes it so light. You can think of them as a sponge which is hard like pumice. But, when you think of a sponge, remember that mostly Aerogels aren’t very resilient. That means, unlike sponge they won’t get back into the previous shape after they’ve been pressed a lot. They are much sturdier/tighter than sponges. A small (not very small; due to very low density they occupy large space) piece of Aerogel weighing just 2 grams has been shown to hold a 2.5 kg brick without deforming. Poorly made Aerogels, on the other hand can also not be very sturdy. They would deform with a hard press of a finger and stay deformed.

How light are they?
Agreed, they can be lighter than air, but the practical mass varies greatly. And they don’t float in air because, with air present inside them, they are slightly heavier than air (weight of air inside + solid material), but can be made to float in air by replacing the air inside it with Hydrogen or Helium. Their lightness and density is completely dependent on the amount of porosity included during the fabrication – which can be controlled. Also, the kind of gel used to make it, affects the weight of the final block. So a block with 3 feet in length, breath and height can weigh anything from 1 kg to just 160 gm.

Aerographite, a carbon Aerogel made by German material scientists from Kiel University and the Hamburg University of Technology, was said to have weighed only 0.2 mg per cubic centimeter. It was 5000 times less dense than water and 6 times lighter than air (counting only the solid material’s weight of course). [Published Paper]

Graphene Aerogel: As if that wasn’t enough, recently, Chinese material scientists developed a lighter material than Aerographite. It was based on Graphene. A Graphene Aerogel; seven times lighter than air. This one, unlike other silica Aerogels, can recover like a sponge after getting deformed. [Published Paper]

Other Properties

Aerogels exhibit various other desirable properties which make them useful for a myriad of applications [See the Wikipedia Article]. For instance, they are very good insulators of heat. A nicely made Aerogel block which is just under a centimeter thick can protect things from a direct flame. Other desirable properties are high surface area, high thermal and acoustic resistivity, low dielectric constant, and low refractive index.

Aerogels absorb water or moisture from the air and even from human skin easily. Handling them with bare hands can cause blisters. But, the ones which repel water have been made successfully by altering fabrication parameters. Also, if particles of it are inhaled, it can cause problems. Hence, hand gloves and respiratory masks are used to handle them.

I want to study interesting materials like these

If you think Aerogels and Wolverine’s claws are interesting things. You can make a career in researching materials like these by making a foray into Materials Science and Engineering. Most good universities offer a course in it. It is a budding field, growing at a rapid pace with loads of opportunities waiting for you.