Raise Your Force Fields!

Science Fiction has a common thematic element – space ships “Raise Shields” to create an invisible force field that protects them from damage (if you have a week to waste, you may want to check out TVtropes – just try and not follow the links…).

But force fields are just science fiction, right? Well, no – we use the term force fields in physics to mean an area where a “force at a distance” is acting. It doesn’t work in the same way as SF force fields work, but it does do something similar. In SF, force fields work like an invisible barrier or wall that nothing can pass through. In physics, something that is affected by a force field will change direction as it is affected by the field. The most common “force field” you experience every day – gravitational fields. We will save that for year 12. This year, it is necessary for you to understand how Electric Fields operate.

In class, we already experimented with the Van De Graaff Generator, which generated a static charge which could be transferred to other objects (like getting someone’s hair to stand on end, or pie pans to float), induce imbalanced charge in other objects (the confetti experiment), or discharge (when a spark was generated by the close approach of the grounding wand).

Each of these is explained in some detail in another post I have on this blog – which I expect that all of you will read. (CLICK IT NOW – you will forget to do it if you wait!) What we need to look at in some more detail is what happens when you have an excess of charge.

While Van De Graaf generators generate a small amount of charge, you can generate far more charge with bigger devices. For those of you who have played Command and Conquer (Red Alert), you may have wondered about the Tesla Towers used in the game. They are real, and were invented by Nikola Tesla, a Russian inventor, and almost the classical example of the mad scientist. Tesla developed a device that built up enormous charges,Β  now called the Tesla Tower

The Tesla tower is used in science experiments, but it can be far cooler – check out the following performance by “Arc Attack”:

The amazing part of that performance is that much of the “music” is actually produced by the electric discharges (“lightning bolts”). The plasma generated by the discharges can be “tuned” so that it creates particular sounds, and thus the musical performance.

See you in class!

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37 Comments on “Raise Your Force Fields!”

  1. darrren10 Says:

    Haha the guy in the Tron suit is my new hero XD
    so does the suit absorb the plasma or does it absorb the electricity and then how does it work πŸ˜€
    also, is it possible to build one without spending a lot of money.
    also is this similar to how electric guitars work?

    • CyberChalky Says:

      It doens’t absorb electricity – it acts as a conductor to allow the arcs to discharge across the surface.
      I wouldn’t suggest trying to build one at home! It is expensive and quite possibly lethal…

  2. Prathu Khairnar Says:

    WOAH!!! do u watch doctor who sir???… great, i am not the only one then πŸ™‚

  3. Jack Says:

    Hey sir! The post you linked with this post is good information.

    By the way, I didn’t think telsa cords could create music! I’ve seen something similar to the video above in The Sorcerer’s Apprentice, http://www.youtube.com/watch?v=U2CNIJ21ooo&feature=related

    but dismissed it as some Hollywood trick πŸ˜›
    But now that I know it’s possible….. I must add that onto my bucket list πŸ˜€

    • darrren10 Says:

      haha in primary school i remember got to go on an excursion to something like this with the telsa towers and the cage thing πŸ˜€
      though there was never music, just loud bangs and crackly ><

      • darrren10 Says:

        Wow, hey jack, let’s build one of these πŸ˜€

        they hooked it up to a keyboard and now the mini tower does a similar thing using a keyboard as the control πŸ˜€

      • Jack Says:

        I know :O I saw it on facebook. However i question the legitimacy of that video :\ i don’t see any safety measures being taken to avoid getting electrocuted. Either way, good find Darren πŸ™‚

  4. Prathu Khairnar Says:

    that seriously does not look safe :O… *runs away*

  5. leileix Says:

    woah, that was amazing~~!!!

  6. Rares Luca Says:

    guys this is quite interesting
    πŸ˜€ peace out

    • Jack Says:

      Pretty Cool Rick! However, I do question whither or not that couch is a good insulator, or else the charge on his body would escape him.. i assume that’s how electricity works, please correct me if im wrong πŸ™‚

      • Rares Says:

        I don’t know jack I just put the video on for people to enjoy:D πŸ˜› but the couch looks pretty isulated. I just find this amazing and i want to do it:D.

        Thanks for the repply jack:)
        Peace Out

    • Paktia.Z Says:

      Lol, wanna see him just get fried.

  7. prathamesh Says:

    side note: this is static electricity by the way…
    Any AC or DC electricity’s properties are differnt than static electricity.

    Once the static energy is discharged it wont cause another spark again

  8. Levy Says:

    HI SIR!

    wow. i didnt know that the Tesla Tower could make those sounds :O its awsome!

  9. Brendan Says:

    What does Ohms law state and why?

    Ohms law is the formula R=V/I which states the relationship between current, potential energy (voltage) and resistance. It states that current and PE are directly proportional to each other. This proprtionality is resistance. When current and voltage are plotted on a graph resistance is equal to the gradient of the line formed because resistance in a circuit cannot change even if PE and current do.Β 
    Checkout page 42 of our physics book for some more info on ohms lawΒ and a picture/video will be here soon when i figure out how………

  10. Andy Says:

    What are 2 factors of Ohm’s Law? I think that was it :/ lol.
    2 are Resistance and Voltage. but i dunno why

  11. darrren10 Says:

    Cool, so my question was, why does a V-I graph have to start from the origin. So as stated by Ohm’s law, the current to voltage ratio has to be the same. On the y-axis, where y is 0, the x value has to be 0 as well. If it started somewhere eles, then x would not equate to y and therefore would not be ohmic.

    and here’s an informative video, kinda neatly puts ohms’s law, voltage and current up nicely together πŸ˜€

  12. Paktia.Z Says:

    My question was: What is a current divider?, ill try answer as best as I can.

    Current dividers are the inverse of voltage dividers, voltage dividers work with series circuits, while current dividers remains constant. They work with parallel circuits as long as the voltage is the same across all components, and any series circuits must be combined before using the current divider equation
    [img]http://upload.wikimedia.org/math/6/7/d/67defed23f74e450ec50124b9e5b779e.png[/img]
    Current divider refers to splitting current between the branches of the divider.

    //Will edit when decent video is found.

    Sources: http://engineersphere.com/basic-electrical-concepts/current-divider.html
    http://en.wikipedia.org/wiki/Current_divider

  13. Paktia.Z Says:

    My question was: What is a current divider?, ill try answer as best as I can.

    Current dividers are the inverse of voltage dividers, voltage dividers work with series circuits, while current dividers remains constant. They work with parallel circuits as long as the voltage is the same across all components, and any series circuits must be combined before using the current divider equation

    Current divider refers to splitting current between the branches of the divider.

    //Will edit when decent video is found.

    Sources: http://engineersphere.com/basic-electrical-concepts/current-divider.html
    http://en.wikipedia.org/wiki/Current_divider

  14. Mitchy Says:

    so all as i get fromthis i when and how can i play with electricity like that guy,with out going benjimin franklin style

  15. Jack Huynh Says:

    Question: Why is the gradient of an Ohmic device constant?

    Answer:
    Although there is no true Ohmic device since it is relatively hard to keep a constant physical conditions such as temperature, the gradient of an ohmic device is always constant since it expresses a repetitive ratio between voltage and current.

    In addition to this, the line on a graph is always linear, and when choosing two points on a linear graph, we can see that they both relatively have the same x to y ratio.

    Eg, y = 2x. Point 1 ( 4, 8) Point 2 (6, 12). What we can see from this linear graph is that for the ratio between these two variables are 1:2.

    By using these two points we can figure out the constant gradient Resistance by: V2 – V1/ I2 – I1.

    Some more information can be obtained from the site linked below:
    http://www.a-levelphysicstutor.com/elect-concepts-units.php

  16. Jack Huynh Says:

    Point 1 : ( 4, 8 ) <– haha! 8)

  17. Zaki Zulkafli Says:

    Question: Why do Ohms device never have a negative charge.

    Answer: Ohmic’s devices are never negative, it always has to have a positive charge because as the voltage increases, so does the current or in other words, increasing heat means increasing resistance.

  18. Lovleen Lovleen Says:

    Hello,
    my question was…
    Why a curve line in V-I or I-V graph not a ohmic device?
    I think it is because a curved line will show a definite increase or decrease in current. Which means there is a change in resistance.
    and in a true ohmic device, the resistance remains a constant. Which means that the the device will never heat up. And as something heats up, it gains resistance.
    This is why a curved line in a I-V or a V-I graph is not an ohmic device.
    Hope it’s right… correct if wrong
    thank you

  19. Dylan Says:

    What are two properties of an ohmic device?

    Well metallic and non-metallic resistors are considered Ohmic devices.

    And for something to be considered ohmic it must obey OHM’s law in that the ratio of V/I is constant and when plotted on a graph a Straight (linear) line is produced.

  20. Mitchell Says:

    Describe the hall way circuit? the circuit consist of two 3 pole switches a twin activ to connect the switches a power source and a load normally the light globe, it works by using the twin active an the 3 poles switches it makes a gateway between the circuit flipping one switch on will turn it on by connecting the circuit and when you turn the other switch off it switches to the other active disconnecting the circuit will upload picture when I’m not on my phone well diagram.

    Hallway circuit

  21. Dylan Says:

    Awesome arc 500kv

  22. alvin Says:

    my question was, what is a voltage divider?
    Are resistors connected in series across a voltage source (wire), used to recieve the desired voltage in the circuit.


  23. […] Electricity: Fields, Resistance, Static […]


  24. […] have two posts about this topic already (1, 2), and I suggest that you read them –Β and all the comments and links! – after you finish with […]


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