What is Positive and negative: Definition and 52 Discussions

In mathematics, the concept of sign originates from the property that every real number is either positive, negative or zero. Depending on local conventions, zero is either considered as being neither a positive number, nor a negative number (having no sign or a specific sign of its own), or as belonging to both negative and positive numbers (having both signs). Whenever not specifically mentioned, this article adheres to the first convention.
In some contexts, it makes sense to consider a signed zero (such as floating-point representations of real numbers within computers). In mathematics and physics, the phrase "change of sign" is associated with the generation of the additive inverse (negation, or multiplication by −1) of any object that allows for this construction, and is not restricted to real numbers. It applies among other objects to vectors, matrices, and complex numbers, which are not prescribed to be only either positive, negative, or zero. The word "sign" is also often used to indicate other binary aspects of mathematical objects that resemble positivity and negativity, such as odd and even (sign of a permutation), sense of orientation or rotation (cw/ccw), one sided limits, and other concepts described in § Other meanings below.

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  1. M

    I Force between Positive and Negative Electrical Charges

    I have in the past been criricised for inappropriate postings that I could have resolved with research so this time I have done the research first. The best solution I have found is from wiki "that causes it to experience a force when placed in an electromagnetic field." What causes the force...
  2. A

    Solving Cross Section Confusion: Adding Positive and Negative Ions

    ik that i have to add the positive and negative ions but the cross section (surface) confuses me how do i resolve this?
  3. YMMMA

    Magnetic force direction on a positive and negative charges

    Homework Statement The question askes about the path of the electron. I need to know if I am doing it correctly whether it was asked for a proton or an electron. Homework Equations F=QV⊥Bsinθ The Attempt at a Solution I answered it C. Because it is an electron, I used my left hand. My thumb...
  4. Gene Naden

    Positive and negative plane wave solutions of Dirac equation

    I continue to be occupied with the first chapter of Lessons on Particle Physics by Luis Anchordoqui and Francis Halzen. The link is https://arxiv.org/PS_cache/arxiv/pdf/0906/0906.1271v2.pdf. I am on page 24, where they derive equations 1.5.67, which are: ##(\gamma^\mu p_\mu-m)u(p)=0## and...
  5. S

    Potential difference in between positive and negative charge

    Homework Statement Two point charges Q1= +5.00 nC and Q2 = -3.00 nC are separated by 35.0cm. What is the electric potential at a point midway between the charges? Homework Equations V = Ke(q/r), PE = Vq[/B] The Attempt at a Solution This question is from Serway textbook. The answer is...
  6. A

    Finding the final speed of a Positive and Negative Charge

    Homework Statement This is an example problem I found on khan academy and it didn't have an official problem statement... So I am going to have to make up my own problem statement from what was given. I can link the video if any of you want to see it. A positive charge 4uC and a negative...
  7. Allen_Wolf

    B Exploring the Possibility of Negative Mass: Implications and Limitations

    If we imagine two particles A and B. A has positive mass and B has negative mass and initial velocity 0. This happens in a non interfering environment . If both theses has opposite and equal value of mass, shouldn't they be repelling each other? F=G. (M.-m)/r^2. Value of F should be negative.
  8. S

    Chemistry Determining the positive and negative poles of a molecule

    Homework Statement For the molecule CHCl3, a) Draw the electron dot diagram and structural formula b) predict the shape c) predict whether it is polar or non-polar, and justify your prediction. Indicate the positive and negative poles. Homework Equations none The Attempt at a Solution [/B]...
  9. E

    Attraction of a positive and negative charge

    No one could ever explain to me the mechanism how attraction of positive and negative charge works. Can you? (Exchange of (virtual) photons only explains repulsion.) An electrical field is playing hide and seek.
  10. Kuzon

    What is the difference btwn positive and negative electrodes

    I'm so confused, is the voltage reading of the meter gathered by: positive electrode charge - negative electrode charge = potential difference I don't get why there is a positive and negative electrode and what they do
  11. Mr Davis 97

    B No distinction between positive and negative for imag nums?

    I am solving for the square root of a complex number, namely: ##\sqrt{5 -12i}## Let's assume for brevity's sake that I already have the solution ##3- 2i##. This is fine and well, but the book that I am reading goes on to say that "##- (3 -2i)## is an equally valid solution, since there is no...
  12. T

    What's the Difference Between Positive and Negative?

    I am aware of what positive and negative polarities are but what specifically causes the distinction between positive and negative polarity?
  13. D

    Positive and negative work in terms of energy.

    How would we define positive and negative work in terms of energy? When the force and displacement are in opposite directions, we say the work done by the force is negative. When the force and displacement are in the same direction, we say the work done by the force is positive. However, how we...
  14. bigsmile

    Positive and negative signs on Work

    Homework Statement An amount of work equal to 1.5 J is required to compress the spring in a spring gun. ? Homework Equations Wtotal = change of KE[/B] The Attempt at a Solution W=ΔKE=(1/2)m(Vf² - Vi²) It sounds like the Vf >0 and would be maximum after the spring is compressed hard and...
  15. ericdmurphy

    Positive and Negative Adjustable Current Supply (3.3mA)

    Hello, I was looking for some sort of chip/IC that would accept a digital input of say 4-5 bits and that would adjust an output current. I am looking to have a +/-3.3mA current applied to a resistive load. It would also be helpfull (for testing purposes) if I could adjust the inputs so that I...
  16. Akhilesh Kumar

    What Determines the Electric Charge of Fundamental Particles?

    We have been able to explain the reason for the mass of a particle to a great extend... But till now why are we not getting a clear idea of why does a particle has charge?? What gives a particle its charge??
  17. Neil Graham

    Differences in Repelling Charges

    Simply, is there a difference between a positive charge repelling a positive charge and a negative charge repelling a negative charge. More of what I am asking, is there any special properties that one has over the other, and vice versa.
  18. Aristotle

    Uniformly Charge on a Wire - Electric Field

    Homework Statement (Just for number 1 only - finding electric field) [/B] Homework Equations dE = k dq/R^2 sin theta = y/R = y / sqrt (a^2 + y^2) dq= lamda*dy The Attempt at a Solution [/B] I'm confused at the point of calculating the integral from -L/2 to L/2. I got the final integral...
  19. tesla420

    Variations of +/-; Can there be more than just positive and negative particles?

    Is there any evidence that suggests there can be more than just positive and negative particles
  20. K

    Is There a Difference Between Positive and Negative Charge Light?

    Is there any difference between light produced by a positive charge and light produced by a negative charge?
  21. C

    Direction positive and negative charges will movebetween electrodes?

    Homework Statement If a small positive and negative charge are created at rest at a point between electrodes as shown in the figure. In which direction will they move if one would neglect gravity? Ignore those weird arrows, those are for later questions. Homework Equations...
  22. A

    What is the relation between positive and negative charges?

    Is it the absence and presence of an electrical fluid called as positive and negative charges?
  23. A

    Why there are so many positive and negative ions in N and P types?

    The image bellow is the PN junction under equilibrium. I wonder why there are so many positive and negative ions in N and P types respectively. For me, I think that these ions should only exist in the depeletion region not outside the region. Thanks for help.
  24. anorlunda

    Both positive and negative curvature?

    What happens to the Reimann tensor at the event horizon of a black hole? Do some of the 24 components become zero or infinite? What happens to parallel transport of a vector on the surface of an event horizon that is different than on a surface outside the event horizon? I'm newly educated...
  25. P

    How do I multiply positive and negative numbers? (in n's complement)

    Homework Statement I need to understand how signed multiplication is done in 2's to 10's complement.Homework Equations The complement D' of a number D with m digits in base r is rm - D. So, the complement of 010 in binary (2 in dec) is 1000 - 010 = 110 (-2, but 6 if it were unsigned). We add a...
  26. C

    What is the difference of positive and negative charge?

    Hello I am aware of what generates the electric charge of each particle, the virtual fotons around it that the particle generates, and that when two particle interact with each other a foton is exchanged and so forth. My question is though, what generates the positive and negative charge, and...
  27. J

    Difference between positive and negative flow in wires

    Does anyone know if I run 12 volts dc at 1 amp power for a distance of 250 feet and one wire is 12 gauge used for positive and other negative wire is 20 gauge will the smaller ground wire affect what the positive wire can carry? John
  28. R

    Help needed Analyzing a real op amp with both positive and negative feedback

    Hi this is my first subject in this forum and i hope you can help 1.we have been given an assignment to analyze this non-ideal op amp with both positive and negative feedback and to be honest i don't even know where to start i know i should post an attempt of trying to solve but honestly...
  29. H

    If electricity is flow of electrons and also positive and negative

    if electricity is flow of electrons and also positive and negative charges attract then why electricity needs a conducting medium. electrons has mass and it should just travel through vaccum then why in vacuum electricity cann't travel please reply!
  30. J

    Geometric series - positive and negative ratio

    Hello, Second term of a geometric series is 48 and the fourth term is 3... Show that one possible value for the common ratio, r, of the series is -1/4 and state the other value. ar=48, ar^3= 3... so ar^3/ar=3/48 which simplifies to r^2 = 1/16, therefore r = 1/4 Can anyone explain where...
  31. Fredrik

    F is integrable if and only if its positive and negative parts are

    Homework Statement Problem 2.6.3. in "Foundations of modern analysis", by Avner Friedman. Let f be a measurable function. Prove that f is integrable if and only if f+ and f- are integrable, or if and only if |f| is integrable. Homework Equations Friedman defines "integrable" like this: An...
  32. S

    Basic Question: Positive and Negative Electrical Charge

    I am not a student of Physics. I want to know. I am curious. I never understood a basic thing. What is the difference between a positive and a negative electrical charge? What characteristics describe the two charges? Are they just something you mug up as a given example of the duality in the...
  33. S

    What is positive and negative eigenspaces? Can you recommend me a

    What is positive and negative eigenspaces? Can you recommend me a referance to know them?
  34. R

    Positive and Negative 5v from 2 AA Batteries

    I'm designing a portable device running off of 2 AA batteries that requires positive both positive and negative 5v power at the same time. What is the best/cheapest way to achieve this?
  35. AJKing

    [Intro Chemisty] Positive and negative charges.

    I'm just learning but I can almost SWEAR that this is right, just reassure me?
  36. O

    How to divide positive and negative charges from each other

    How to divide positive and negative charges from each other without them interacting with other matter or charge patterns. ,please answer I only need this to make my ultimate machine
  37. K

    Positive and negative square roots

    how to determine which is the answer to positive sqrt and negative sqrt in this problem? substituting works but what if the equation is very long and you can't use calcu or computers http://i.imgur.com/SkcQZ.png also is there a way to solve this without squaring both sides?
  38. A

    AC Voltage at Point X on Wire: Positive and Negative Half Cycle

    greetings, consider a wire which is subjected to AC supply.now consider a point X anywhere on wire. now what will be the potential of that point during the positive and negative halfcycle of sinusoidal AC?what will be the direction of current? thanks
  39. pellman

    Signicance of positive and negative frequencies?

    Reading some QFT in which we are faced with inhomogeneous equation (\partial^\mu \partial_\mu + m^2)\phi(x)=J(x) The solution is given as \phi(x)=\phi^{(+)}_{in}(x)+\phi^{(-)}_{out}(x)+i\int{d^4 x\Delta(x-x')J(x') where \Delta is the appropriate Green's function. "in" means the...
  40. K

    Why do positive and negative charges attract?

    These questions, being so basic, were harder to find answers to on the forums (or elsewhere). At least, it was harder to find an answer that satisfied my curiosity. I need a DEEPER, simpler, and more logical understanding of these concepts.: What does it mean for a particle to have a positive or...
  41. L

    What is the role of positive and negative controls in an experiment?

    Homework Statement Could anyone explain to me what exactly is positive and negative control in an experiment? Homework Equations The Attempt at a Solution
  42. P

    Positive and negative electrical terminals

    I am slightly confused as to why some circuits are drawn with a positive input terminal and a negative input terminal, whilst others are just drawn with a positive terminal and a ground (OV) terminal. What is the difference between ground and negative? Does negative indicate an excess of...
  43. S

    When is friction and weight parallel positive and negative?

    Homework Statement When writing Fnet=ma you are supposed to list the forces in Fnet -Ffriction + Weightparallel= ma how do you know when to put the negative or positve sign in front of the values? like on inclines and horizontal surfaces Homework Equations The Attempt at a Solution
  44. maverick280857

    Exploring the Meaning of Positive and Negative Energy in the Klein Gordon Field

    Hi everyone The Hamiltonian of the Klein Gordon field can be written as H = \frac{1}{2}\int d^{3}E_p \left[a^{\dagger}(p)a(p) + a(p)a^{\dagger}(p)\right] and we have [H,a(p')] = -E_{p'}a(p') [H,a(p')] = +E_{p'}a^{\dagger}(p') The book I'm reading states that What does this mean? Thanks.
  45. I

    The difference btn positive and negative potential quantum well

    Homework Statement (a) Determine the reflectivity spectrum R(E) of a free particle of mass m reflected from an infinite jump V(x), where V(x)=0 if x\leq0, V(x)=-\infty if x>0 The other similar problem is: (b) Determine the energy levels of a particle of mass m confined to an infinite...
  46. F

    Is Work Being Done? Investigating Positive and Negative Work in Various Agents

    Hello! I need a help with one question: Discuss weather any work is being done by each of the following agents, and if so, wether the work is positive of negative. a) a chiken scratching the ground (what I think is that work is performed as W=F∆x, and if the chicken moves her leg back and...
  47. N

    Explore the Complexities of Positive and Negative Numbers

    You probably think that adding one to zero gives you one. But, let us examine this process a little closer. Imagine being at absolute negative infinity. I know, you are probably thinking that infinity goes on forever, which indeed it does, and therefore we cannot comprehend the point at...
  48. Loren Booda

    News The United States: your positive and negative

    The U.S. seems caught in a love-hate relationship with the rest of the world. What would you say is our most admirable quality, and what the most detestable?