What is Green: Definition and 306 Discussions

Green is the color between blue and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495–570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content.
During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers and the gentry, while red was reserved for the nobility. For this reason, the costume of the Mona Lisa by Leonardo da Vinci and the benches in the British House of Commons are green while those in the House of Lords are red. It also has a long historical tradition as the color of Ireland and of Gaelic culture. It is the historic color of Islam, representing the lush vegetation of Paradise. It was the color of the banner of Muhammad, and is found in the flags of nearly all Islamic countries.In surveys made in American, European, and Islamic countries, green is the color most commonly associated with nature, life, health, youth, spring, hope, and envy. In the European Union and the United States, green is also sometimes associated with toxicity and poor health, but in China and most of Asia, its associations are very positive, as the symbol of fertility and happiness. Because of its association with nature, it is the color of the environmental movement. Political groups advocating environmental protection and social justice describe themselves as part of the Green movement, some naming themselves Green parties. This has led to similar campaigns in advertising, as companies have sold green, or environmentally friendly, products. Green is also the traditional color of safety and permission; a green light means go ahead, a green card permits permanent residence in the United States.

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  1. W

    News Green Solution to a Political Problem?

    As Iran continues to develop nuclear power for peaceful purposes, many people have expressed concern that a nuclear weapons program might emerge. http://www.cfr.org/publication/16811/ President Obama has acknowledged they have a legitimate right to pursue peaceful energy development...
  2. T

    Seeking Companion Text to "Green/Papa" Rudin for Measure Theory

    Hey, I was wondering if anybody knew a more intuitive, less axiomatic book that one could use as a companion text to the "green\papa" rudin? (Real and Complex Analysis). I am finding that it is possible to learn measure theory from this book, but it takes a lot of time and rigor. It might be...
  3. J

    Green Products and the Economy

    I am a cabinet maker, and recently, I have had a lot of demand for E0, as they learn that Formaldehyde emissions from many building products are hazardous to your health. "Sources of Formaldehyde Pressed wood products (hardwood plywood wall paneling, particleboard, fiberboard) and...
  4. L

    What Causes the Green Tint in Some Meteors?

    Hello, I have a question for the astronomy people here. Last night I was outside around 10 P.M, and at one point I just happened to be staring up into the western sky when I saw one of the brightest, most beautiful meteors I have ever seen. The weird thing is that it had a faint green tint to...
  5. D

    Green lasers: how much power is too much?

    I saw some green lasers on dealextreme recently, they have units that go up to 200 mW: http://www.dealextreme.com/details.dx/sku.1997 This thing looks a bit unsafe to me! My intention is to show the daughters some stars here in our polluted skies, not much else. How much power is needed for...
  6. C

    Engineering Civil Engineering and Green Energy?

    Does anyone know what sorts of opportunities are out there for CE's in Green Energy (such as solar and wind)?
  7. K

    Engineers Working on Sustainable Energy: Wind, Solar & Hydro

    Which engineers are working the most on sustainable energy such as wind, solar, and hydro? I'm guessing mechanical and electrical. Any other ones?
  8. M

    Odds in Probability of Green Eyes

    Homework Statement Of 27 students in a class, 11 have blue eyes, 13 have brown eyes, 3 have green eyes. If 3 students are chosen at random what are the odds of the following occurring? Only 1 has green eyes.Homework Equations Odds = P( s )/P( f ) = P( s )/( 1 - P( s )) Probability success = P(...
  9. I

    Single slit Diffraction using green light

    Homework Statement Monochromatic green light of wavelength 546 nm falls on a single slit with a width of 0.095 mm. The slit is located 75 cm from a screen. How wide will the central bright band be? Homework Equations D sin 0dark = m 入 The Attempt at a Solution Can...
  10. J

    What color does a green cloth appear in yellow light

    Homework Statement what color does a green cloth appear in yellow light Homework Equations The Attempt at a Solution i know its either green or black but i don't know which. Yellow light is either a wavelength of its own or a mixture of green and red, that's where my problem is...
  11. J

    What color would a green cloth appear in yellow light

    Basically I wanted to teach myself about light and I have a question that i am not to sure about basically I know about the spectrum of light but I also know that two primary colours make a secondary color. yellow is either is own wavelength or its a mixture of green and red, so here's my...
  12. S

    How many phtons are emitted by green light?

    Homework Statement How many photon/s are emitted by a green light (λ= 500 nm) 60 W incandescent bulb? Assume an efficiency of 2%. Homework Equations c= wavelength(f) c=speed of light E=hf The Attempt at a Solution im not sure which equation to use here, i don't know what to...
  13. N

    Efficient Methods of Green House Heating

    Hello. I'm planning on building a green house in my garden with a wind powered heating element to help sustain higher temperatures. I live in a windy area (North Sotland) so wind prevolance is no problem. Would an element be the best way to this or are there better methods of converting...
  14. Math Is Hard

    Cotton Bowl Morning: Fried Green Tomatoes

    This snapshot was sent to me from somewhere near the Cotton Bowl this morning. http://i210.photobucket.com/albums/bb29/jellyroll2008/friedtomatoes.jpg mmmm..MMM! I'd kill for some fried green tomaters.
  15. lisab

    Who's Invited to the Green Wig Party for Borek's Birthday?

    Happy Birthday Borek!
  16. Andre

    Is Last Night's Sunset a Sign of the Green Flash Phenomenon?

    Last night we had the most bright and beautiful sunset I ever saw look at the color of the clouds The start of a green flash? And later in the evening:
  17. W

    Why Did Earth's Early Oceans Have a Green Hue?

    According to the History Channel documentary How the Earth was Made (DVD), Earth's early oceans were green, b/c of their (different) chemical composition. For example, they had more dissolved Iron, and CO2. CONCLUSION: Earth Early Lifeforms were confined to the Oceans, for lack of an Ozone...
  18. D

    Which Crazy Green Idea Will Win the Next X Prize?

    Remember the X Prize Foundation? In case you forgot, the X Prize Foundation is the group that awarded the $10000000 Ansari X Prize to SpaceShipOne four years ago:http://space.xprize.org/ansari-x-prize. Has anyone seen the new video-submission contest to determine the X Prize Foundation's...
  19. M

    Green Planet (My project for energy)

    Hi Everyone, My teacher gave me a project to created anything that need not to be build out physically. I gave the tittle green planet. So the idea is that one could create a VACUUM tunnel from the north to south pole (or any 2 points that is a diameter of the earth) and a "vehicle"...
  20. T

    White peppercorns and green peppercorns

    I just bought some pepper. I didn't know what kind to get so I bought the kind that has its own grinder built in. Then I had to chose between the black peppercorns or the peppercorn medley. I got the medley and it has black peppercorns, pink peppercorns, white peppercorns and green peppercorns...
  21. E

    Can green plants reverse entropy?

    Entropy is said to always increase. But do not green plants reverse entropy? Seems to me that everything they do increases order, down to the molecular level.
  22. M

    RGB LEDs in series - turn Green on

    Hello, I have a high power RGB LED with common anode. I want to have 3 of them in series, and put them on 15V power supply. And I want to switch green color on, and red color as well (something like a normal traffic light) Here is the problem: Given that three LEDs are in series, and are...
  23. D

    No Green Stars: What's the Story?

    Stars seem to occur in almost every color, from red to near violet, but not green. Why are there no green stars?
  24. M

    Classical electrodynamics - Green function

    Hello, I don't fully understand the meaning of Green function, and how one should use it. According to Jackson's "Classical Electrodynamics" - 'the method of images is a physical equivalent of the determination of the appropriate F(x, x') to satisfy the boundary conditions'. Where Green...
  25. V

    Determination of pKa Bromocresol green

    i am having problem in calculating pKa in my experiment,a formula of pKa=pH + log10 [HB]/[B] my data obtain only gotthe pH of HB,that is 5.17 how can i calculate the pKa?? [HB]=concentraion of undissociated form indicator [B] =concentration of dissociated indicator
  26. I

    Why Iron Produces Green Light in Visible Spectrum

    Homework Statement Iron produces many lines in the visible spectrum when given energy. Suggest why a sample of iron sulphate only produces lines in the green section of the spectrum. Sorry if it doesn't sound very scientific, I am recalling the question from memory since I've already handed...
  27. R

    Green Function and Boundary Conditions

    Hey folks, I'm trying to find the Green function for the equation -\partial_\mu \partial^\mu \phi = K where K is some source term. Its a 2D problem with the wave confined to a rectangular cavity where the cavity is located at z = 0 and z=a. This tells me that G|_0= G|_a=0 I've pretty...
  28. Phrak

    Get Green Electrons: Solar and Wind-Powered Electricity Subscription

    If I subscribe to this service, I get my electricity from solar and wind power. But how do I know I'm getting green electrons into the meter?
  29. R

    Green Function approach is more physical?

    Hey folks, I'm not really sure which forum to put this question in but I figured this was probably the best as it deals with issues of regularization. I'm reading Miltons 'The Casimir Effect'. In chapter one he derives the Casimir energy for a massless scalar field by employing...
  30. R

    Green Functions and BC's

    Hey folks, I'm trying to get a handle on my old Nemesis, Green functions. I have a massless scalar field confined between two parallel plates separated by a distance a (in the z dimension) and the field satisfies Dirichel BC's. Basically I'm trying to work from line 1 of a book to line 2 (K...
  31. T

    Green identity, poisson equation.

    Suppose \phi is a scalar function: R^n\to R, and it satisfies the Poisson equation: \nabla^2 \phi=-\dfrac{\rho}{\varepsilon_0} Now I want to calculate the following integral: \int \phi \nabla^2 \phi \,dV So using Greens first identity I get: \int \phi \nabla^2 \phi \,dV = \oint_S \phi...
  32. snoopies622

    The Mystery of Red & Green Light Combinations

    Red light mixed with green light produces yellow light. Yet, a red photon and a green photon don't combine to make a yellow photon (or two of them). Can someone explain this?
  33. T

    Solar Energy and Green House Effect Question

    Homework Statement Negelcting internal heat sources, the surface Temperature of the Earth is calculated to be 255 K. Its actual mean surface Temperature is 288 K. The additional heating results from the greenhouse effect. Regarding this as an internalk heat source, calculate that heat source...
  34. Ivan Seeking

    Extend Freshness with DEBBIE MEYER™ Green Bags®

    https://www.greenbags.com/?cid=402572 On face of things this claim sounds reasonable to me, but really I have no idea. They claim to be good for ten uses.
  35. A

    Thin film red light green light interference

    Homework Statement A mixture of red light (wavelength vacuum = 652 nm) and green light (wavelength vacuum = 477 nm) shines perpendicularly on a soap film (n = 1.333) that has air on either side. What is the minimum nonzero thickness of the film, so that destructive interference removes the...
  36. MathematicalPhysicist

    Another Green function question.

    find the eigenfunctions and eigen values of the next equation: d^2y/dx^2+u_n^2y=0 where y(0)=0=y(pi). Now find the green function of the above non-homogeneous equation, i.e: d^2G_{\lambda}(x,a)/dx^2-\lambda G_{\lambda}(x,a)=\delta(x-a) where a is in (0,pi) and lambda doesn't equal the...
  37. ZapperZ

    VOTE Photo Contest - Green Acres

    This week, people are free to interpret the theme as they wish, although some has taken it into a direction that I never thought of. So please vote for the picture that best represents our theme : Green Acres 1. larkspur 2. turbo-1 3. hypatia 4. BobG...
  38. MathematicalPhysicist

    How do I find the nth-eigenvalue of the eigenfunction u_n?

    I need to find the green function of (\frac{d^2}{dx^2}-k^2)\psi(x)=f(x) s.t it equals zero when x approaches plus and minus ifinity. Now according to my lecturer I first need to solve the homogenoues equation, i.e its solution is: psi(x)=Ae^(kx)+Be^(-kx) and G(x,x')=\sum...
  39. ZapperZ

    Photo Contest - Green Acres (3/8-3/14)

    Green Acres Green acres is the place for me. Farm livin' is the life for me. Land spreadin' out so far and wide Keep Manhattan, just give me that countryside. New York is where I'd rather stay. I get allergic smelling hay. I just adore a penthouse view. Dah-ling I love you but give...
  40. Ivan Seeking

    Help Change the World: Share Your Ideas for Green Homes

    I am in the unique position of being able to implement ideas for green homes immediately for production. If you have any ideas that you would like to share, we will consider your ideas and may use them. It is a chance to help change the world a little bit. Yes I do benefit from this but not...
  41. W

    Green Functions: A physicist's Intro to Math Methods

    Not sure if this is the best place, but it's also my first post, so meta-answers about where I'm supposed to put this business are welcome too. I'm a physics student, and I'm interested in learning about Green functions, but I sold back the Boas book that I used for my math methods class (we...
  42. Ivan Seeking

    Medical Dark Green Blood In The Operating Theatre

    http://www.medicalnewstoday.com/articles/73473.php
  43. G

    Green Tech Career Path for Physics Majors

    I am a physics major, what would be a possible route into green technology? What kind of grad school would I look too? Phd physics or engineering? And what would I specialize in at grad school ? I guess there are all kinds of technologies that could possibly be used ie: solar, hydorgen...
  44. I

    Why Does Glass Look Green at the Edge? - Get Help Now

    Glass is Green? when the glass is viewed at their edge , it looks green . 1.why it is green when viewed at the edge ? 2.Why its not green when we view other than the edge ? i think polarization is the effect but if so,how does it take place . please help me in this...
  45. Q

    So how much of a do you actually give about the whole 'green' thing?

    so how much of a **** do you actually give about the whole 'green' thing? is it really worth worrying about in your opinion? someone just sent me this http://www.guardian.co.uk/environment/treadlightly?CMP=OTCTreadLightly2 you register, they give you 'green' tasks to do, and you...
  46. Y

    Exploring Sodium Acetate and Ammonium Nitrate for Green Architecture

    i am a total newbie here...i understand basic principles like supercooling, phase change, etc, but otherwise a total dummy, i have equivalent to 1st yr university in chem, but that was a long, long time ago. so go easy on me. i am trying to find out the difference btwn sodium acetate...
  47. M

    Bromocresol Green as an Indicator

    Give an example of a titration assay in which bromocresol green could be used. In your example give the concentrations of each component. Based on the conditions of the titration, calculate the pH at equivalence. Since Bromocresol Green has a pKa of 4.6, I figured that this must be a...
  48. R

    Higher Dimensional Green Function

    Hey folks! I'm starting with the Lagrangian of a massive scalar field and have found an expression for the expectation value of the energy-momentum tensor. <T_{\mu \nu}>=(\partial_\mu \partial_\nu-\frac{1}{2}(g_{\mu \nu}(\partial_\mu \partial_\nu+m^2))G(x-x') let say I have some Green...
  49. A

    Is it safe to use a military grade green laser to start fires?

    Does anyone have one of those military grade green lasers that can set things on fire? I've seen people build them but I don't have a solder iron :(
  50. M

    Can You Burn Anything with a 5 mW Green Laser?

    Is it possible to burn anything with a 5 mW green laser?
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