Category: Science and Tech

[Video] Measure Speed of Light Using Microwave

By Anupum Pant

Microwaves are a part of the electromagnetic spectrum. That means they travel at the speed of light. And since it’s known that most commercial microwaves use a frequency of 2450 MHz or can be found on the user manual of your microwave, the speed of light can be calculated using a very simple experiment. Involving just you, your microwave, a pizza and a ruler. You could even use chocolate or marshmallows to do this.

To find the speed of light, all you need to know the frequency and the wavelength because frequency multiplied by the wavelength of an electromagnetic wave gives you the velocity of light. The wavelength of a microwave being used to heat your pizza is fairly easy to calculate. Here’s how:

Make sure the rotation plate is stopped for this cook and then put in a large pizza on a flat microwavable dish. Start the microwave in the lowest power for a long time and keep looking inside. You’ll see that the cheese will start melting unevenly. At that moment it starts melting, switch it off and take the pizza out. Now measure the distance between the centres of molten cheese points. It usually comes to about 6 cm. Multiply it with two to get the wavelength and then finally use the frequency to find the speed of light.

Velocity = Frequency ´ Wavelength

This works because the microwave heats pizza the most, at places where there is a peak in the electromagnetic wave. All the points where the wave seems to be not moving are the places where the pizza heats the least. Turns out, the two nearest peaks (the highest point and the lowest point of the wave, where the cheese first melts) in any electromagnetic wave are separated by a distance of half the wavelength. It makes sense when you see the diagram below. This is the reason most microwaves use a rotating table to heat up your food evenly.

wavelength

How Much do Clouds Weigh?

By Anupum Pant

Oh clouds! Yes, the ones that seem like feather light cotton candies floating high up in the sky. They actually can contain huge amounts of water and can weigh as much as a jumbo jet!

Cumulus clouds which are typically a kilometre in width can contain about 500 tonnes of water, or could weigh as much as 100 elephants or 2,500 donkeys. And yet, it stays floating up there. How!?

Clouds have water distributed in form of innumerable tiny droplets across a huge space. For example, their usual density is equivalent to a teaspoon of water spread out in a volume of a small closet. Or about half gram per centimetre cube. They are so less dense that they are lighter than air. So they float up in air like a ball full of air would float on water.

Once the density of water starts increasing in a cloud, and the millions of tiny water particles start combining, they start forming relatively heavier droplets that ultimately fall out of the cloud. This comes down in the form of rain.

If you like that you’d probably also like raining frogs.

The Hot Chocolate Effect

By Anupum Pant

Have you ever tried tapping the bottom of a pan full of boiling soup? I do it all the time. And unless I hear that low hollow sound, I don’t consider the soup as cooked.

Tapping the bottom of a pan, with boiling soup in it, makes a significantly hollow sound. The frequency of sound that comes from such a tap seems to be much lower than what you’d actually hear if you tapped the bottom of a pan with same amount of cold still water. This effect has a name and is called the hot chocolate effect. Here is how it works.

Water is about 800 times denser than air. Also since air is 15,000 times more compressible than water, sound travels faster in water, than in air. Sound travelling faster in a medium (water in this case), creates a standing wave that has a higher frequency than a standing wave created in a column of some other medium which is less dense (like air).

Boiling liquid, or specifically boiling soup has a lot of air bubbles trapped in it. As a result, the average density of the liquid + air concoction decreases, and the compressibility becomes much higher. This makes the sound travel much slower in it.

So, the sound that comes from tapping the bottom of a container full of thick boiling liquid with a lot of air bubbles trapped in it makes that low-pitched sound. I find it extremely satisfying. Moreover, it is good to know that they  have a name for it!

How Fast Do Electrons Actually Move in a Wire?

By Anupum Pant

Unlike Alternating current which reverses polarity several times in a single second, direct current doesn’t do that. It is a unidirectional flow of charge. So, if you have an extremely long wire, with a switch in between, that connects a little battery in Dubai and a tiny bulb in San Francisco, how long do you think it would take the bulb to light up, when the switch is turned on?

It’d be almost instantaneous. “Almost” because it’d have a huge but finite speed. And by “it” I mean the speed at which the charge flows. Not the electrons.

The speed at which charge or electricity travels down a cable is actually the speed of the electromagnetic wave, not the movement of electrons.It is fast and depends on the dielectric constant of the material.

Electrons in an electric wire move very slowly. So slow, that it would be wise to measure their speeds in millimetres per hour. That is almost like honey flowing on a 2 degree incline. And yet, electricity is able to move across so fast because an electric wire is like a pipe filled with marbles (where marbles are electrons). When you push a marble from one end of the pipe, the marble at other end comes out, without the marble itself moving through the pipe.

Read more [Amasci]

Broccoli is Man Made

By Anupum Pant

Do you remember those massive, muscular Belgian cows? Those super cows were a result of patient selective breeding over many years. No steroids of genetic modifications were involved. Well, there’s something else very similar to how these cows came into existence, which you probably see everyday and yet never realize. Broccoli!

Several years back, probably 1000-2000 years ago, there was no broccoli. It came about in existence after some patient horticulturists selectively bred wild cabbage plants. Broccoli is actually a human innovation, which became popular in modern times only when, in the 16th century, farmers in Italy started growing it. It came to England only in 1720 and to America, much later, in the last century.

With every iteration of selection, cabbage plants with larger and tastier buds were selected and reproduced over and over again. Broccoli, to some extent, can actually be considered as a man-made food. In other words, it was invented / designed by man.

Man-made, yes. But not a genetically modified organism. So, your organic broccoli is as organic as anything else which is classified as organic.

via [PonderWeasel]

Making an Acoustic Propulsion System at Home

By Anupum Pant

Imagine you’ve got 2 PET bottles coupled to the ends of a stick and the centre of the stick is suspended using a piece of thread. Now, if you could spin this contraption, using the low frequencies from just a sub-woofer, you could give this phenomenon a fancy name – acoustic propulsion. Sounds like rocket science? It’s far from that…

Everyone must have tried making low whistles by blowing air into an empty coke bottle. The sound that comes out happens due to something called Helmholtz resonance. When you blow in air, the central column of air inside moves much faster than the air that is touching the inside of the bottle  (the air that surrounds the column of air which you blow in). This difference in velocities creates several vortexes inside the bottle, which make the air move inside in a periodic fashion. And a resonant sound frequency is generated.

I’d explain the fancy word – acoustic propulsion – like this:

In simple words, an empty coke bottle in this little sound experiment acts as a box which converts air you blow into sound. Think of it as an engine with a twist that uses heat to turn a crank. Heat being the air you blow, and the crank turning being the sound that comes out. Just that this engine also works the other way. Turn the crank and heat is generated from the other side.

Likewise, what if you put in the sound? Instead of blowing into the bottle, leave it suspended and make it vibrate with an external source of sound, a sub-woofer! If you get the right frequency, you’d generate a resonant condition inside the bottle, generate vortexes and air would come out of the bottle’s opening. This would propel the bottle further! The video below shows you how…

Why is Orange Juice + Toothpaste the Worst Idea

If you are one of those people who like to have orange juice in the morning just after they have brushed their teeth, you probably know how bad that tastes. Drinking orange juice after brushing your teeth brings about a very repulsive taste in the mouth. If you haven’t tried that, try it once. Trust me, toothpaste + orange tastes awful.

Water, fluoride, detergent and abrasives are the four major components of toothpaste. And the most common detergent (used to form foam) is called Sodium Lauryl Sulphate, or SLS. SLS has some strange effects on your taste receptors. It suppresses the receptors which help you taste sweet

Also, it destroys a compound called phospholipid – compounds meant to suppress the bitter taste. These are the two accepted reasons as to why drinking orange juice after brushing your teeth is probably a bad idea.

The Oxygen Stealing Material

By Anupum Pant

If you rely on and make your judgement on just the editorial titles being passed around on the internet, then you got to look more carefully. A few days back, when a few researchers from Denmark announced that they had developed a material, a tiny volume of which could store huge amounts of oxygen, the whole internet saw a headline floating around that said something like:

A new material, just a spoonful of which can suck up oxygen of the whole room.

That sounds like a material which every serial killer on the planet would  be waiting to get their hands on. However, the real story is quite different, from what the headlines make it look. Which is also not to say that the invention is any less remarkable.

Think about it like this – A single spoonful of this material (more like a bucket actually) sure has enough space to store the amount of oxygen that normally is available in a single room. But, unlike what headlines tell you, it can’t spontaneously pull all the oxygen from the whole room in a few seconds.

Since a tiny volume  of it can hold so much oxygen, this new material, made by tinkering of the structure of cobalt, will probably, in the near future, be a boon for patients who have to lug around heavy tanks of oxygen with them. Deep sea divers will benefit from it too, not serial killers. The video explains.

The Underwater Vacuum Cleaners

By Anupum Pant

If you didn’t know, most white sand you see on some beaches around the world, has at some point in time, passed through a fish called the parrot fish. It’s an amazing ecological role the parrot fish plays.

An interestingly similar ecological role is served by a marine animal with a very leathery skin called the sea cucumber. Professor Ove Hoegh-Guldberg explains why these organisms have such an important role in the marine environment.

Basically, while scavenging for algae or minute aquatic animals, sea cucumbers ingest a lot of sand. As it passes through their bodies, the digestive system increases the pH of the sand, making it more basic. When this comes out, the sand is clean and turned basic. This way it plays a chief role in countering the negative effects of ocean acidification.

It also helps coral reefs survive by supplying them with calcium carbonate (a by product of its digestion process) and helping them maintain a net inflow of calcium carbonate.

The ammonia that comes out also makes the bed more fertile, making it much more suitable for coral reefs to grow.

Watch these underwater vacuum cleaners in action below.

Faking Sleep Affects Performance

By Anupum Pant

A couple of days back I talked about how standing for a few seconds in a superman position could increase your level of confidence and could help you ace interviews. Today it’s time again to look at a technique to increase performance by fooling your body.

First of all, you need to stop thinking you didn’t sleep well today. That is because the mere act of thinking you slept well makes you perform well. It’s been proven.

In a group where everyone got equal sleep, half of the people were just told by “experts” that they had 29% REM sleep (which is better) and the other half were told that they had only 16% REM sleep (that actually decreases performance). The catch was, they all had slept for equal times and everyone would have had more or less equal percentages of REM cycles. Only, they were told wrong things by “experts”.

This word of mouth coming from the “experts” actually affected the performance of these two groups. The group that was told they had a greater percentage of REM sleep performed well. And the group that was told they did sleep as well as the first group didn’t perform as good. I’m assuming both the groups were first informed about how the percentage of REM sleep affects performance.

So, stop cribbing about how tired and sleepy you  are.

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.

Hornets are Able to Harvest Solar Energy

By Anupum Pant

Wasps are active during the day time, and hornets too. It is during the morning (and the day time, when the sun is out) when they carry out most of their activities like digging into the ground. In fact, there’s a reason why they do it all mostly during the time when the sun is out.

The brown and yellow coloured stripes they have on their bodies are good to warn predators. Besides that they also serve one other interesting purpose – to harvest solar energy!

Researchers have figured that the brown and yellow stripes on the bodies of hornets and wasps have special kinds of gratings that help them to absorb most light, without reflecting much of it. With these gratings they are able to funnel in light from the sun by increasing the surface area for more efficient absorption.

It is believed that when the sun is out, the yellow and brown bands wasps and hornets have on their bodies are able to absorb sunlight and are then able to convert it into electrical energy – which they, purportedly, use to conserve energy and carry out metabolic functions. Researchers also believe that they use up this energy to dig up nests and fight other insects.

Here’s what the paper says:

The complex structure of the cuticle is produced by extracellular secretion from the epidermis. It is constructed as a composite consisting of chitin filaments, structural proteins, lipids, catecholamine derivatives, and minerals. The Oriental hornet cuticle (the exoskeleton) exhibits a brown-yellow pattern…The yellow segments protect the cuticle from potentially harmful solar UV radiation, similar to the role of melanin in the brown color segments of the hornet’s body…The yellow segments contain xanthopterin, which is housed in an array of barrel-shaped granules…the voltage between the hypocuticle and the exocuticle of the yellow stripe showed a negative potential at the hypocuticle with respect to the positive exocuticle. In response to illumination of the yellow stripe, the difference in potentials between light and darkness increases…The fact that the Oriental hornet correlates its digging activity with insolation, coupled with the ability of its cuticular pigments to absorb part of the solar radiation, may suggest that some form of solar energy harvesting is performed in the cuticle.

– (Plotkin et al. 2010:1075)

Source [AskNature]

Jellyfish Stings and The “Pee on it” Myth

By Anupum Pant

I haven’t been ever stung by a jelly fish, but from how Destin says it in the video, and other people I’ve seen getting bitten, tells me that it is something no one would want to experience in their life. If you did not know, the sting is awfully painful.

A jelly fish uses venom, not poison. They are two different things. Which means that a jellyfish stings you and uses extremely tiny hypodermic needle like things to inject toxins in your body.

But doesn’t jellyfish seem like a bunch of jelly floating around with no visible prickly parts? how does something so soft actually go about inserting something sharp into your skin?

Turns out, on the surface of those long tentacles these fish have, there are microscopic organelles called nematocysts which it uses to sting you. Even a tiny brush with those tentacles can trigger them. The more interesting part is that these tiny needles act very fast, and like I said, they are also very tiny. So, to see them you need a really high frame-rate camera attached to a microscope.

That is exactly what Destin does in the video below. It’s fascinating to see those tiny stingers do their work so fast under a microscope. Not many get a chance to see something like this.

Just FYI. In case you ever end up getting bitten by a jellyfish, please don’t ask your friend to pee on it. There’s a word going around that this helps, but in reality it doesn’t. In fact it can make it worse. Instead try washing it off with sea water. And then use a credit card to scratch the sting to remove any nematocysts stuck in your skin.

Don’t believe me? Please watch this…

[Video] Making a Perfect Ice Sphere

By Anupum Pant

Ice cubes are too mainstream. Moreover, considering the greater surface area cubes have (as compared to spheres), they melt too quickly. Who’d want that in their drink?

So, here’s a device that can make ice spheres using just gravity, in under a minute.

The simple aluminium mold isn’t powered by any heat engine. It simply works by pressing the ice cube and conducting heat really fast. Also, using the perfect amount of pressure so that it doesn’t crack the cube. It works because aluminium has a high thermal conductivity. 

The end result is a perfect ice sphere made out of an ice cube in under a minute. No heating involved.