Do you know , each and every thing we do, we owe it to electricity. From Lightning to sparks , every thought that enters your mind , why a dog barks or a cat chasses a laser beam, all of this involves electricity!





WHY A BALLON RUBBED ON HAIR STICKS TO THE WALL?

Have you ever tried this? Take a thin piece of balloon( I will explain later why it should be thin) and rub it vigorously on your hair, and take it close to a wall, IT STICKS!!! How does this happen ? What possibly could be the reason that the balloon counteracts Gravity and sticks on the surface of the wall. Is it friction, or something else?





Well the answer is INDUCTION.

You must have done a small intresting experiment in school, where if you rub a comb over your hair, mound a few small pieces of paper and then take it closer , the paper is attracted by the comb, easy! But did you notice that some of the paper falls back faster than other, why does that happen?





So when two materials are rubbed against each other, something interesting happens. One of them gains a certain charge, and the other one looses a certain charge. When a silk cloth is rubbed against a glass rod, silk aquires electrons and glass looses some, so silk develops a negative charge and glass positive. A series which shows how easily something gains or looses electrons on rubbing is called the TRIBOELECTRIC SERIES, (Tribo is Greek for rubbing.)





TRIBOELECTRIC SERIES

In the triboelectric series, the substances at the top have a tendency to give away their electrons, while at the bottom have a tendency to gain an electron.





As you can see, comb made of plastic or rubber is right at the bottom of the list, whereas human hair at the top, thus on rubbing the hair gains a positive charge whereas the comb a negative one.





So when you rub the balloon made of plastic against your hair, the same thing happens, balloon gains a negative charge and hair positive.

The induced charge on the wall because of the balloon.





When a charged balloon is placed near a wall, the balloon induces charge in the wall. The electrons in the balloon repel the electrons in the wall further away, and thus make the side of the wall closer to the balloon positively charged. And thus because of the attraction between the balloon and the wall, the balloon stays put!





BUT WHY DOES THE ATTRACTIVE FORCES DOMINATE OVER THE REPULSIVE ONES?

Well that's an excellent question, here is the answer. The positive part is a bit more closer to the electrically charged balloons than the negative part, and since these electrical forces are inversely proportional to square of the distance(Just like Gravity) the attractive forces dominate over the repulsive ones.





As rubber is a insulator and the area of contact between the rubber balloon and the wall is small , it takes sometime for the charge from balloon to flow into the wall and neutralize, and thus the attractive forces of the charges dominate over Gravity and the balloon sticks to the wall.

If your balloon does not stick , either it is too heavy (That's why I recommended a thin balloon) or the air is humid, it contains moisture. Dry air is a pretty good insulator, it does not let the charge from the balloon escape, but for some complicated reasons, moist air allows the charge to leak into the air, and thus the balloon looses it's charge, the attractive force weakens and Gravity pulls the balloon down, and so it falls. This is why the best time to do this experiment is in winter, when the air is dry



HOW DOES A LIGHTNING OCCUR?



Although, there are about 43,000 lightning strikes every day, about 1800 every hour of the day and about 100 lightning strikes each second, we don't completely understand the working behind a lightning, although in order to understand it, we must first learn what is potential difference or Volts.



POTENTIAL DIFFERENCE(VOLTS)



Named after Alessandro Volta, the inventor of cell, which we now call battery, it is the energy produced to move 1 Coulomb of positive charge from Earth to a positively charged object . The potential difference here is +1 Volts. The energy needs to be produced since there is a repulsion between like charges. Similarly the energy we need to produce to move 1 coulomb of negative charge from Earth to a negatively charged body is -1 Volts . Remember current flows from high potential to low potential, and earth has zero potential.



LIGHTNING SPARKS AND CRACKLING NOISES.



We don't really understand how or why, but during thunderstorms, the top of the cloud becomes positively charged, and the bottom negative. By induction, the part of the Earth closer to the cloud becomes positively charged and the one away from it negatively charged, and thus a huge potential difference is created. This potential difference allows the current to flow, and this heats up the gas, or ionizes the gas between the clouds and the Earth. Due to this, a lot of charge flows through this region and we see a spark.



This ionized hot gas moving around the cooler gas creates a pressure wave, which we hear as sound. Speed of sound in air is about 340 meters per second, so depending on the number of seconds the sound takes to reach you, you could calculate the distance to the lightning strike. Also the hot ionized gas splits up the oxygen molecule into each oxygen atoms, and these unstable oxygen atoms combine with O2 molecule to form Ozone(Oxygen with 3 O atoms in it). Thus during lightning we smell a distinct odor, which is ozone! You might not notice it in cities(because of air pollution), but its very much obvious in rural areas.



UNEXPLAINED MYSTERIES.



There's still many things that we don't know anything about, like the red sprites and the blue jets that are seen high up in the sky during lightning strikes between the thunder and space. The reason why we don't understand these well enough yet is that they were discovered about 30-40 years ago, and there's a lot of research going on in these fields because of satellites and other telescopes.

A picture of the blue jets captured over China, photo credit:Phebe Pan



Isn't it wonderful that just by rubbing a balloon over your hair, you can understand and unlock the secretes of nature? Electricity is all around us , and we very much take it for granted, also be careful while playing with electricity, it can be very lethal sometimes! But keep exploring nature, wondering about the way she behaves, subtle, intricate, and above all elegant. Isn't it wonderful that just by rubbing a balloon over your hair, you can understand and unlock the secretes of nature? Electricity is all around us , and we very much take it for granted, also be careful while playing with electricity, it can be very lethal sometimes! But keep exploring nature, wondering about the way she behaves, subtle, intricate, and above all elegant.

"Nothing is too wonderful to be true if it be consistent with the laws of Nature"

-Michael Faraday.

Article by:Shanawaz Shaikh. (F.Y.BSc)