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Electrostatic telegraphs (case study)

Long before the internet people thought about sending information along wires using static electricity. Created by Brit Cruise.

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  • leaf green style avatar for user 福龍丸
    Dual question: is it really 'pitfall', 'pithfall' or something else?
    Is it the plant's name or the little ball we call 'pit(h)fall'?
    (13 votes)
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  • leaf green style avatar for user Dane Sheridan
    I don't understand why the amber attracts the hairs when rubbed against fur. Does anyone know why?

    Thanks, Dane
    (10 votes)
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  • mr pants teal style avatar for user box 0f rox
    At , I don't understand why you have to touch the metal plate before removing it from the insulator.
    (12 votes)
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  • leaf red style avatar for user Blake weber
    what is the plate and ball made out of?
    (8 votes)
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  • leaf red style avatar for user Blake weber
    another question, when you create the charge on the copper wire, over time would the static charge weaken or stay the same?
    (5 votes)
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  • aqualine ultimate style avatar for user Erin (Hexaflexagon!)
    Is this the same as when I wear footie pajamas, rub my feet against the carpet, touch my siblings or metal and then they get shocked or I shock myself? Can someone please explain how this is related or not related?
    (3 votes)
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    • male robot hal style avatar for user Enn
      Yes, that is caused by static electricity.
      Like when amber is rubbed with fur, the fur loses some electrons to amber to become positively charged while the amber becomes negatively charged similarly carpets may have a tendency to lose electrons or give electrons depending on the material of the carpet and shoe due to friction.
      If a person gains electrons and becomes negatively charged and touches a metal or any good conductor of electricity then the electrons will jump out giving a shock.
      If a person became positively charged and touches a good conductor then electrons will jump to the person giving a shock.
      The shock will feel the same irrespective of whether the charge jumps to the person or out of the person.
      (9 votes)
  • leaf red style avatar for user Ian
    Point of curiosity: at , what phenomenon causes the water to bubble around the wires?
    (2 votes)
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  • leaf green style avatar for user wailokmonad
    I have problem understanding how the charge would be first pulled into the metal plate from the insulator, and then miraculously trapped in It simply by putting a finger to it.

    What is more, things become so amazing that this charge-trapping process could be repeated for many times without the insulator being recharged. However, I become puzzled why this process must be preceded by first putting a finger to it. Why not directly put the plate to the insulator? Why bother with this additional step? What is the theory behind all these things?
    (2 votes)
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    • purple pi purple style avatar for user APDahlen
      Hello Wailo,

      The answer is electrostatic induction. Ref: https://en.wikipedia.org/wiki/Electrostatic_induction

      Let's start with a charged insulator. For sake of discussion let's assume it is negatively charged (excess electrons).

      When we put the metal plate on top of this charged insulator the electrons in the metal plate do what electrons do best. They try to keep as far from other electrons as possible. Since the insulator has an excess of electrons the plate's electrons tend to congregate in the side opposite the insulator.

      When you touch the plate these excess of elections are removed from the plate. Think of this as an equalization between the underside of the insulator and the top of the insulator. Assuming you and the lower part of the insulator are at the same potential.

      Later when the plate is lifted it is no longer in equilibrium. It has a deficit of electrons because you removed them with your touch a few steps back.

      I challenge you to build an electrophorus. Search the web and you will find many ideas. Please leave a comment below and let us know your success.



      P.S. Just for fun see https://www.youtube.com/watch?v=rG7N_Zv6_gQ&t=362s
      (3 votes)
  • blobby green style avatar for user Elijah Penny
    Does that mean that amber is a conductor?
    (3 votes)
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  • starky ultimate style avatar for user Simon Dreyer
    Is it possible to charge a type of battery with lightning?
    the power from lightning is very sustainable. Is it possible, if not, then why?
    (1 vote)
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    • mr pink red style avatar for user Varun
      It isn't currently possible (although we never know what future science may achieve) because there's just so much energy. There are millions of volts and ten thousands of amps of energy in lighting. We just can't capture and store that. We can create lightning by using a transformer and a capacitor to convert regular electricity into lightning, but reversing the process is considerably harder since lightning strikes for such a short period of time. Capacitors store energy over time that can be released in a burst like lightning, but we don't have a tool that can take a burst and slow it down and release it over time.
      Hope this makes sense.
      (4 votes)

Video transcript

Around 600 BC Thales of Miletus widely regarded as the first Greek philosopher. As he was the first to give a purely natural explanation of the phenomena he observed. A key observations he made was that certain stones such as amber when rubbed against fur would exhibit a strange property. The amber seem to emit an invisible force which would attract small fibers. And he assumed that this rendered amber magnetic another force he observed when playing with lodestone which are naturally-occurring magnets. Many after him observed that the contact or friction with fur seem to create an imbalance. Something was pulled from the fur and transferred onto other objects. Now, not only did this result in a small attractive or repulsive force but also in the potential for shocks to occur. Once the discharge occurred the force disappeared. So the shock with some form of discharge which reversed the imbalance created by the friction. Throughout history we're also fascinated with lightning bolts. Nature's most passionate displays of power and aggression. Most cultures assume this was a divine force outside the reach of human hands and was therefore reserved for the gods. Up until the 17th century, our descriptions of it varied from an invisible, intangible, imponderable agent or even threads of syrup which along gate and contract. And it was Benjamin Franklin, who in 1752 set out to prove that there is a connection between lightning and these tiny shocks due to friction. In a famously dangerous experiment done alone with his son, he let a kite into a thunderstorm and near the bottom where the thread was wet, he tied an iron key and after some time he brought his knuckle up to the key experienced the series of small shocks identical to the ones created by contact with fur. This showed that indeed, lightning was simply the same thing is these household shocks but on a massive scale. And at this time people have begun to divide materials into two categories: one were objects which would allow or accept discharge such as gold or copper which we call electrical conductors. Interestingly these materials are also generally good at conducting heat. And number two were objects which would not allow this discharge such as rubber or electrical insulators. These materials also seem to insulate the transfer of heat and we also began trying to measure this force that Thales had encountered. One way to do this was to suspend the piece of spongy plant called the pith ball from a thread and when we rubbed an insulator against fur and brought it near the pith ball it would pull on it causing a deflection. If we had more objects we noticed deflection increased due to a greater pulling force. We also noticed that the shape of insulators made a difference. Large thin insulators seem to exhibit a much stronger force. (soft bell ring) And amazingly, it was found that conductors such as copper wire would transmit this pulling effect over a distance. This was demonstrated by running a long wire between the pith ball in the charged insulator. When the object was brought near the wire it pulled through the wire and deflected the pith ball instantly. When we later touched the wire with our finger discharge occurs and the pulling stops and the ball is released. Immediately people began speculating that this could be the future optical telegraph. In 1774 French inventor George Louis Le Sage was one of the first one to record actually set up this idea. He sent messages through an array of 26 wires each wire representing a letter of the alphabet. When a discharge occurred at one end the pith ball would move at the other. The trouble with this telegraph was that it only extended between the two rooms of his house. The power the deflection was small and difficult to work with. Though at the time people were investigating techniques for generating larger charge differences in order to amplified a force involved. One improvement popularized by Alessandro Volta one year later was an easy wave generating discharges on demand. It was based on the idea that a charged insulator could induce or transfer the charge onto a nearby conducting plate. One needed to merely bring the metal plate close to the insulator which would pull on the charge distribution in the metal plate resulting in an imbalance or electrical tension in the metal plate. Then one could bring their finger to the plate in it discharge would occur then the plate is pulled away using insulating handle and an excess charge would remain trapped in the plate to play could then be discharged at will simply by touching it to a conductors such as a finger and amazingly this process can be repeated many times without recharging the insulating plate. We could then generate many small discharges at will. And by now Benjamin Franklin was focused on finding out how to trap or store up these discharges. At this time he still assumed that electricity with some sort of invisible fluid Since we knew it could travel through water so we assume that water inside in insulator could hold electricity. What we now call the Leyden jar was a glass jar with water inside and a metal probe running at the top. Franklin also wrapped the outside in a conductive metal. When he brought a charge conductor towards the top probe a discharge would occur and stay trapped in the jar. More importantly was that the jar could be charged multiple times. Each spark would amplify the charge separation for electrical tension inside the jar. A good analogy is to think of the jar as a balloon and each discharge as a short jolt water. And after hundreds of iterations the tension become massive. And to release the charge he simply touch the outside conductor to the probe. A large discharge occurred. Franklin improved the design over time eventually realizing that the charge was not stored in the water but glass. The water was merely a conductor path from the probe to the jar. Today we would call the Leyden jar a capacitor or charge storing device. And when he chained many jars together he found he could increase the capacity even more and release deadly volt of electricity. And over the years people focused on more effective ways a building up charge using friction machines which could then be stored in capacitors and relief the spectacular displays of man-made lightning. And over the next 50 years people tried to design systems for sending sparks across greater distances using longer wires and more powerful discharges. However sending electrostatic discharges as a communication method seemed clumsy archaic and was no improvement over the existing optical telegraph of the day. They were widely ignored by government and industry. Though the tides were rising. An electric revolution was just around the corner.