What is Filament: Definition and 69 Discussions

The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. According to the sliding filament theory, the myosin (thick) filaments of muscle fibers slide past the actin (thin) filaments during muscle contraction, while the two groups of filaments remain at relatively constant length.
It was independently introduced in 1954 by two research teams, one consisting of Andrew F. Huxley and Rolf Niedergerke from the University of Cambridge, and the other consisting of Hugh Huxley and Jean Hanson from the Massachusetts Institute of Technology. It was originally conceived by Hugh Huxley in 1953. Andrew Huxley and Niedergerke introduced it as a "very attractive" hypothesis.Before the 1950s there were several competing theories on muscle contraction, including electrical attraction, protein folding, and protein modification. The novel theory directly introduced a new concept called cross-bridge theory (classically swinging cross-bridge, now mostly referred to as (cross-bridge cycle) which explains the molecular mechanism of sliding filament. Cross-bridge theory states that actin and myosin form a protein complex (classically called actomyosin) by attachment of myosin head on the actin filament, thereby forming a sort of cross-bridge between the two filaments. The sliding filament theory is a widely accepted explanation of the mechanism that underlies muscle contraction.

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  1. F

    B Formation of Brown Dwarfs in filaments?

    Hello, I'm in grade 12, writing a term paper on brown dwarfs and am currently looking at their formation. I have now come across the formation of brown dwarfs in so-called "filaments" (link to the page below), but can't find out anything about them, except for the fact that they are filamentary...
  2. Slimy0233

    I Heating a tungsten filament to find out the maximum brightness emitted

    I was taking notes from a lecture on Quantum Physics and during the introduction, they gave an example of what led to the discovery of Quantum Physics: The electric bulb example where the brightness and colour of light depended on the temperature of the filament(see...
  3. J

    Electrical Old filament car lamp to LED

    I want to change the the old round 5000 series filament bulbs to led. I attached a picture of some I found on Ebay. I see some led bulbs seem to mention some thing about fan. One way would be cut hole in old glass bulb and glue led in with silicon. Could use glass jar and drill hole in cover...
  4. E

    Electronics Why is my W filament burning in my DIY electron gun project?

    I'm in a project that make electron gun myself. I made acryl cylinder for the body and used W(tungsten) filament that using in real SEM. I made the body vaccum(about 11kPa), and applied voltage to the filament(about 6V). Then, the filament started to be heated. But problem was appeared. I didn't...
  5. Baibhab Bose

    Temperature of a thin bulb filament

    In my assignment question, the length L and radius r is given and asked to find out how the Temperature of a thin bulb filament which depends on those two parameters. and the answer is r^(1/4)*L^(-1/2). I can't figure out how. Which relation is involved?
  6. ephphatha16

    Resistance of a tungsten filament bulb at 20 C

    I was looking for any credible sources who could reveal the resistance of a normal tungsten filament bulb at room temp 20 C? I heard its cold resistance is about 9.5ohms. Is that the resistance at rtp? Thanks a lot in advance!
  7. Simon Clement

    Incandescent bulb filament

    Hello here Why is it necessary that the filament of an Incandescent bulb to have low evaporation rate below melting point?
  8. Iftekhar Uddin

    How an Electric Field is affected by an Insulator

    I looked through this forum post for an answer to my problem. It gave me enough insight to try and come to some conclusions but I'm still confused on some parts here and there about how I got my final answer. 1. Homework Statement A uniformly charged, straight filament 7.70 m in length has a...
  9. P

    Adiabatic switching time of a filament lamp

    Hello all. Firstly I am sorry if this is in the wrong place but I was unsure exactly where it fits in as it involves physics, integrated equations, and computer programming. I am trying to write an emulator for a machine which is running 256 filament lamps in a 16*16 matrix. I want to simulate...
  10. A

    Final Temperature of a Lightbulb filament

    Homework Statement When an incandescent light bulb is switched on, it can take a few moments for the filament to fully heat up and reach its equilibrium temperature. Assume the filament of a given light bulb is made of Tungsten, and also assume the potential difference across the filament is...
  11. G

    I Filament for thermionic emission in open air

    I’m looking for material capable to act as filament of thermionic emitter in open air. Classical tungsten filament is not capable, because it readily oxidizes. We experimented with filaments made from SiC and ZrO2 (Yttria stabilized). At 1900K SiC provides certain degree of emission, but it is...
  12. H

    How to determine temperature of filament?

    I was wondering in class today how I could determine the temperature of a filament in an incandescent light bulb? Mainly then so I could determine the thermal energy outputted through radiation. So after school I used a test circuit. I started with the Stefan-Boltzmann law which is Q =...
  13. A

    Current flow model through a resistance field

    Hey everyone. I thought about this problem the other day, but I don't know what theory I need to solve this problem. Given a 2D rectangle with a known, varying resistance, and a known voltage drop across the length, how would one calculate the current density at each point on the surface. By...
  14. R

    Filament lamp model (derivation)

    Homework Statement State and use simple assumptions to show that ' Power is proportional to V^5' is the expected relationship for a pure tungsten filament bulb. Homework Equations V=IR I=dq/dt Q=mcT The Attempt at a Solution I tried to use a simple model where the rate of heat loss is...
  15. Plat

    I Measuring vacuum w/ hot filament - calculation (pirani gauge)

    I am looking for guidance on how to successfully measure vacuum using a device similar to a pirani gauge, my device however is a tungsten filament which is heated electrically to about 90*C, and it's current draw is a measure of vacuum.The problem I am having is how to relate specifically the...
  16. M

    Halogen light bulb filament thicknesses?

    Hello, new to the forum, just a average guy, not too much more informed on physics then the average person, so this will be a pretty simple question, anyway, to my question: with halogen bulbs, does higher wattage always mean thicker filament? Because i am trying to work out if tricky Chinese...
  17. C

    Solving Filament Failure Mode with Maths

    Homework Statement Not homework but this seems the best place to post this. In a private conversation someone posted this explanation from a book on how a lamp filament fails.. I'm having some trouble doing the maths to show that the thinner higher resistance part gets hotter... Homework...
  18. D

    Wire supplying current to a filament lamp doesnt get hot?

    Hi everyone, So one of my students has asked me a question which I'm not sure how to answer. The question is: Why does the wire that supplies current to the filament lamp in a light bulb not heat up, even though the filament itself does? Please let me know your thoughts! Thank you :)
  19. E

    The relative resistance of a filament vs. a conductor

    1. I'm a middle school science teacher with no science background, and I'm trying to avoid teaching any misconceptions on this topic! However, I don't know that I grasp what's going on here myself. I'm trying to explain rationale for why, on a circuit diagram, the symbol for a resistor may...
  20. O

    Brightness and temperature of a filament

    Hi again. We have two electric circuits. One is with a thin filament and the other has say 5 times larger filament. It is clear that the 5 times thicker filament is 5 times more powerful: the energy dissipation from electrons to the atoms is 5 times faster, because the current is higher 5...
  21. gfd43tg

    Filament radiation in light bulb

    Homework Statement A light bulb has an internal filament with a total surface area of 2.5 X 10-3 ft2 that operates at a temperature of 2240 F. The filament has an emissivity of 1.0 and radiates through a vacuum to the glass wall of the bulb. Only 10 percent of the total energy emitted as...
  22. E

    Melting a lightbulb filament

    Does anyone know an approximate voltage needed to melt the filament of a typical 120V/60W incandescent bulb? I'm doing a research project and I've calculated 211V. However, I don't have a power supply capable of delivering it - yet. So for now I can't test my theory. and I haven't had...
  23. C

    Voltage over bulb with broken filament

    Homework Statement A main circuit contains six similar bulbs connected in series. One of the bulbs has a broken filament. Voltmeters X and Y of infinite resistance are placed in the circuit as shown. What are the voltmeter readings? A) X=0 Y=0 B) X=0 Y=240 C) X=40 Y=40 D) X=240 Y=0...
  24. B

    What produces the photons in light bulb filament?

    What produces the photons in light bulb filament? I know that electrons are emmitted by thermionic emmission from the filament . . . do they then fall back into the filament and emit EM radiation as they de-accellerate into the filament?
  25. E

    Surface area of a bulb filament

    Does anyone know what it is, or where I can find the surface area of a typical 60W incandescent bulb filament? (if possible, by GE) I'm working on a research project and we're applying the stefan-boltzmann law. I'm calculating an area around 3e-5 m^2. I figure I'm in the ballpark, but I'd...
  26. F

    Temperature of filament using its area, power, and emissivity

    I have entered the emissivity in the calculation so that we can treat it as a blackbody, allowing us to use I_{tot} = \sigma T^4. My book tells me the correct answer is 2.06*10^4, which I'd normally put down to a misprint, but if I use my value, I get a value for the next part which is a factor...
  27. J

    Thin vortex filament with constant circulation; find velocity components

    Homework Statement In a xyz cartesian coordinate system, a thin vortex filament with constant circulation Gamma, forms a square (in the xy plane), with each side of the square having length L. You are told that an infinitesimal segment del (vector) of this filament induces an infinitesimal...
  28. A

    Carbon di oxide emission of filament bulbs

    One thing I am not able to understand. Governments advocate the slow phasing out of the filament lamps and replacing them with CFLs.The reason repeatedly cited for this is that the filament lamps contribute to the global warming by way of emitting carbon-di-oxide. But, interestingly, it is...
  29. E

    Resistance-current characteristic in the case of filament lamp (investigation)

    Changing voltage - independent variable current flowing - independent variable The investigation was aimed at measuring current at different potential differences, before the filament lamp started to shine and when it was shining so as to observe both ohmic and non-ohmic behaviour. Also after...
  30. R

    Best location for a light bulb filament using a concave mirror?

    Where is the best location for a light bulb filament to be placed in a spotlight, when using a concave mirror? It makes the most sense to put it at the focal point of the mirror if you want parallel light beams but are you supposed to have parallel light beams when you use a spotlight? Or do...
  31. T

    What is the surface area of the filament? heat expansion and transfer

    Homework Statement the filament of a light bulb has a temperature of 2580Cel. and radiates 60W of power. The emissivity of the filament is 0.36. What is the surface area of the filament? Homework Equations P= \sigma*A*emissivity*T^4 A=? \sigma=\sigma\ =\ 5.670400(40)\ \times\...
  32. M

    Need an help on filament bulb topic

    need an urgent help on filament bulb topic hi everyone i am getting stuck in this assignment on question related to filament bulb. the question goes like: is resistance and gradient inverse to one another in filament bulb and when looking at the graph (which is a curve graph).. we need to...
  33. A

    Why filament intensity profile of filament lamp deviates from blackboady curve?

    doing experiment today in which the intensity profile of a filament lamp (of surface temp around 2000K I think) is studied by passing it through a rotating grating apparatus and then reading the output from oscilloscope. My question is why the intensity profile intensity profile the...
  34. R

    Modern Physics: Current in Wolfram Filament

    Homework Statement Determine the current in the wolfram filament with the diameter 0.8 mm and the temperature T=2800K, which is maintained constant. Specific electrical resistance of the filament is ρ = 0.92⋅10-4Ohm⋅cm. The temperature of environment is t = 17C. Homework Equations...
  35. P

    Temperature increase in filament due to resistance

    I'm trying to calculate the temperature increase in a filament which a pass a current through. It's a very fine wire, so making direct measurements is difficult. Also, it's stainless steel 310 instead of a standard material. I can adjust the current, but want to correlate how the power...
  36. M

    Electric field at the surface of a filament.

    On a nylon filament 0.01cm in diameter and 4cm long there are 5.0e-8 extra electrons distributed uniformly over the surface. What is the electric field strength at the surface of the filament? a) In the rest frame of the filament? b) In a frame in which the filament is moving at a speed 0.9c...
  37. P

    Tungsten Filament bending and production

    Tungsten Filament bending and production! my machine produces filaments for a UV lightbulb, the filaments are basically tungsten coiled tightly around a tungsten shank, and the machine used to do this perfectly! however it was switched off for a about a year during development. but now when...
  38. I

    Plotting a Suitable Graph to find Emissivity of Tungsten Filament

    Plotting a suitable graph to find emissivity of tungsten It is given that: Q = pσ2πal(T^4 - t^4) Where Q is the Energy Loss Rate, p is Emissivity and T,t are the wire and room temperature. Other symbols are constant. I have data for Q and (T^4- t^4), which for simplification purposes...
  39. C

    Using DC Power to Create Electron Flow in a Tungsten Filament Light Bulb

    If i have a light bulb , and it has a tungsten filament and when i turn it on its gets hot , If i hook a lead to the filament and then put the anode away from the filament can i get electrons to flow through the vacuum , assuming this is done with DC current. If we used 2 different...
  40. K

    Filament lamp I/V characteristics lab problem.

    i have to have my lab report ready in the next 1 hour and i am stuck. in my experiment we had a varied power supply , an ammeter and a voltmetter both with small error (and digital). i have taken about 15 measurements of potential difference and its respective current. the circuit had in one...
  41. K

    Filament lamp I/V characteristics lab problem.

    Homework Statement i have to have my lab report ready in the next 1 hour and i am stuck. in my experiment we had a varied power supply , an ammeter and a voltmetter both with small error (and digital). i have taken about 15 measurements of potential difference and its respective current. the...
  42. K

    Boltzman Constant, Emissivity and Surface Area of a filament

    Homework Statement A tungsten filament in a lamp is heated to a temperature of 2.30 x 10^3 K by an electric current. The tungsten has an emissivity of 0.31. What is the surface area of the filament if the lamp delivers 35.0 W of power? Homework Equations Stefan's Law (a greek letter...
  43. S

    Why is a Tungsten filament used in incandescent bulbs? (Factual Question)

    Homework Statement Why is a tungsten filament used in incandescent bulbs? I earlier thought that it was due to the high resistivity of tungsten , but i was wrong , the resistivity of tungsten is low at 5.2 * 10^-8 Is it due to its high melting point?? I can't figure out as...
  44. N

    Power dissipated in a cylindrical cavity due to a current carrying filament

    Homework Statement A cylindrical cavity oriented along z axis with length of 2 m has a filament in it upon which a current of 10 A is impressed. Cavity is perfectly conducting whereas it is filled with lossy dielectric. Electric field on the cavity is given as: E=-z(i+j). One has to...
  45. S

    Diverging lens on filament

    Homework Statement A diverging lens with focus 5 cm is placed on a filament. Find the distance between the lens and the filamentHomework Equations \frac{1}{f}=\frac{1}{di}+\frac{1}{d}The Attempt at a Solution Focus of diverging lens is negative so, f = -5 cm. I think the question is asking...
  46. R

    Resistivity of tungsten filament

    ]1. A 1.3 cm length of tungsten filament in a small lightbulb has a resistance of 0.032 ohms. Find its diameter. Given: Length= 1.3 cm= .013m R= 0.032 ohms resistivity= 5.6e-8 ohms*meter [b]2. A= pi (r^2) R= resistivity (Length/ Area) The Attempt at a Solution R= resistivity...
  47. R

    Resistivity of tungsten filament

    [b]1. A 1.3 cm length of tungsten filament in a small lightbulb has a resistance of 0.032 ohms. Find its diameter. Given: Length= 1.3 cm= .013m R= 0.032 ohms resistivity= 5.6e-8 ohms*meter [b]2. A= pi (r^2) R= resistivity (Length/ Area) The Attempt at a Solution R=...
  48. S

    Filament size and resistance

    Does anyone have a clear understanding on the relationship between the filament size of a lightbulb and the wattage? I was under the impression that resistance causes the filament to heat up and glow, so the more resistance the brighter the light bulb. A filament with more resistance, then...
  49. J

    Temperature of Bulb Filament

    Homework Statement A common flashlight bulb is rated at 0.3 A and 3.3 V (the values of current and voltage under operating conditions). If the resistance of the bulb's tungsten filament at room temperature (20.0 degrees Celsius) is 1.10 Ohms , estimate the temperature of the tungsten...