Negative Definition and 1000 Threads

  1. N

    Vacuum Chamber: How Long Will It Maintain Pressure?

    The syringe' plunger is in a fully retracted position (non-vacuum state) and is then connected to the tube forming an airtight seal. Then the valve to the vacuum chamber, having 29.9 Hg of vacuum, is opened. I am fairly, certain that the plunger in the syringe will move to its forward most...
  2. S

    Question on positive negative magnetic fields

    1. If the sun is reversing polarity where the northern part of the sun is showing signs of becoming positive and the southern part of the sun is already positive and if two like polarities repel could not the sun ? break in two. 2. question If the sun has two positives end and a negative...
  3. O

    Could neutrino have negative mass?

    Can anyone think of an empirical reason the neutrino could not possibly have a negative mass; that is any of its states?
  4. H

    MHB Manipulation of negative square root of a negative term/#

    Suppose I have to solve for y: x\leq 1 (x - 1)^{2} = y So I know that (x - 1) will always be 0 or a negative, therefore I must take the negative square root of (x - 1): -\sqrt{(x - 1)^{2}} = -\sqrt{y} Am I to understand that this is the same as: -1 \cdot \sqrt{(x - 1)^{2}} = -1 \cdot...
  5. A

    Exploring the Possibility of Negative Changes in Entropy in the Universe

    Negative Changes in Entropy?? Perhaps this is not the right forum location, but I would like to ask some of the more experienced physicists here about the notion of negative changes in entropy in the universe. According to the text I am currently reviewing by Hill, the probability that a...
  6. 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...
  7. T

    Engineering Circuit Analysis: Current flowing from negative to positive?

    Homework Statement http://images.4chan.org/sci/src/1340320682704.jpg I am to write KCL equations for this circuit. Why is it that the current flowing AWAY from Node C is written as V2(t). I thought that when a current was flowing AWAY from a node, the current would be -V2(t)...
  8. E

    Making Flux Negative in a Constant Vector Field Help

    Homework Statement I know I posted a question yesterday also, but this homework is getting on my nerves. My prof isn't the best out there. So basically the question is as follows: http://img812.imageshack.us/img812/8130/problem6.png Homework Equations Not sure, I sort of answered the...
  9. T

    Proving Negative Divisors of an Integer

    Homework Statement Show that negative divisors of an integer, are just the negatives of the positive divisors. The Attempt at a Solution having an integer n and a negative divisor k, we get the positive divisor by multiplying (-1)k, thus each negative divisor of an integer, is the...
  10. M

    Why in scattering processes q^2 is negative?

    Hello, not sure if I'm typing the question in the right place, but I encountered this question when going through Peskin (eq. 6.44, though it's not important). If p and p' are respectively the momentum of electron before and after the scattering, then q=p'-p is the momentum of photon joining...
  11. C

    Calculating Distance for Negative Acceleration

    Homework Statement Suppose an object has a velocity v and an acceleration of a, where a is negative. The object will eventually reach a velocity of zero v = 0. How much distance will the object travel until v = 0? Homework Equations v = u + at s = 0.5(u+v)t s = ut + 0.5 at2 v2 - u2...
  12. E

    Why is the ac output voltage negative for a common emitter Bjt network?

    I get that collector current is fixed so as collector current goes up, the voltage drop across the collector resistor goes up and the collector-emitter voltage goes down. Which is why it is basically zero at saturation. But for ac it is not zero but negative when input is positive. why is this...
  13. J

    Negative Fractional Exponent problem

    Hi All, Can anyone walk me through this problem. This is from an old med school entry test. The answer is 81 but I can't work out how the x terms cancel. 3x(3x^ -1/3)^3 Thanks in advance John
  14. Y

    Nitrogen Systems: First Positive, Second Positive, First Negative

    What is the "first positive", "second positive", "first negative" systems of nitrogen Hello, I have been trying to catch up on spectroscopy theory, and I'm trying to get a grasp on what all the terms mean. I constantly seem the terms "first positive system", etc... coming up, and I'm not sure...
  15. 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
  16. N

    QFT w/ Negative Mass: Spin 0 vs Spin 1/2

    In the Klein-Gordon equation (spin 0), the mass dependence is (only) through m^2, whereas in the Dirac equation (spin 1/2) it's through m. Does this mean that for spin 0 particles, we can just as well describe them as having negative mass without changing any of the physics (whereas for the...
  17. S

    Negative and positive work - Question

    I accelerate a mass upward by 2G (2×force of gravity) over some change in height Δh_{1}, then I apply only \frac{1}{2}G over some other change in height Δh_{2}. If, over Δh_{2}, the mass still moving upward (but accelerating downwards), am I doing positive work over Δh_{2} even though the mass...
  18. V

    Energy - Can energy be negative?

    Energy -- Can energy be negative? Can energy be negative? If yes,can mass be negative?(since E=mc^2)
  19. MTd2

    Accelerated Expansion from Negative Λ

    I think this is one of those papers that will have millions of citations http://arxiv.org/abs/1205.3807 Accelerated Expansion from Negative Λ James B. Hartle, S. W. Hawking, Thomas Hertog (Submitted on 16 May 2012) Wave functions specifying a quantum state of the universe must satisfy...
  20. V

    Negative index of refraction with anisotropy, quick question

    Hey all, I'm trying to solve a problem in which I have a uniaxial (uniform in two directions, different in the other) crystal with the optical axis normal to the plane of reflection. I call the permittivity parallel to the optical axis ε_par and the permittivity in the other two directions...
  21. G

    Determinant of symmetric matrix with non negative integer element

    Let \begin{equation*} A=% \begin{bmatrix} 0 & 1 & \cdots & n-1 & n \\ 1 & 0 & \cdots & n-2 & n-1 \\ \vdots & \vdots & \ddots & \vdots & \vdots \\ n-1 & n-2 & \cdots & 0 & 1 \\ n& n-2 & \cdots & 1 & 0% \end{bmatrix}% \end{equation*}. How can you prove that det(A)=[(-1)^n][n][2^(n-1)]? Thanks.
  22. J

    CDF of a variable with a negative exponent in its PDF

    Ok, this one's got me stumped! Let's take as an example the probability density function for a random variable X so that: f(x) = \frac{4}{3x^{3}} 1≤x<2 f(x) = \frac{x}{12} 2≤x≤4 f(x) = 0 So the CDF for this variable comes out as: F(x) = \frac{-2}{3x^{2}} 1≤x<2 F(x) =...
  23. J

    Negative Energy and Mass Symmetry

    I was wondering about a system, specifically quantum, though classical solutions are still welcome, which was resisting all applications of Noether's Theorem, and related techniques. If a system is invariant under a switch from E→-E AND m→-m, then what are the conserved quantities (in analogy to...
  24. F

    Exploring the Dirac Equation: Positive & Negative Energy Solutions

    Hi! Homework Statement 1. Substituting an ansatz \Psi(x)= u(p) e^{(-i/h) xp} into the Dirac equation and using \{\gamma^i,\gamma^j\} = 2 g^{ij}, show that the Dirac equation has both positive-energy and negative-energy solutions. Which are the allowed values of energy? 2. Starting...
  25. 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...
  26. S

    Negative sequence (Symmetrical component)

    I'd like to know how do i find I2 (Negative sequence current) if I know Ia, Ib and Ic but don't know angle (in normal system_not fault)? My system's 3 phases 3 wires.
  27. D

    High pass filter, output has negative voltage level

    I built a clock generator using a 555 and I fed the output to a high pass filter. It works for the most part, BUT the input voltage ranges from 0 to 5V while the output is -5 to 0 V. I can't figure out why this is happening. I'm new to EE, so bear with me.
  28. R

    Who first assigned negative to electrons and positive to protons?

    Who first assigned "negative" to electrons and "positive" to protons? a sort of history question... the fact that the actual flow of charge (which are electrons in metal conductors) is in the opposite direction of the "positive" current flow in circuits has always been an annoyance to me...
  29. G

    Negative Voltage: Understanding How Current Travels

    I just completed a problem regarding a Millikan Oil Drop Experiment. I ended up with a negative voltage in the solution. I am just trying to understand negative voltage. Does it mean that the current will travel from - to + instead of the conventional + to -?
  30. J

    Simplify & eliminate negative exponents

    Hi there, Please help :) out of school for years started studying again and finding it so hard to pick up the basics again! But am trying very hard! Homework Statement Simplify the expression and eliminate any negative exponents Homework Equations (2x^3)^-2 (3x^4)^2...
  31. 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!
  32. C

    Why does negative feedback stabilize an operational amplifier?

    I'm studying for an exam and I'm struggling to understand op amps, here's my problem: I understand that for an op amp to have a controllable gain, the difference between the input terminals must be very very close to zero (and you can assume it is zero). And to do this you use negative...
  33. T

    Infinite sum of infinite negative series e^(-nt)

    Find the sum of e^(-nt) as n = 0,1,2,3,... Apparently it's 1/(1-e^-t) Can't use normal geometric series formula though as if a =1, r = e? Any ideas Thanks :)
  34. S

    How don't neurons get enough K+ to balance out their inner negative charge?

    If resting potential is negative, then K+ ions shouldn't be passively exiting the cell. It doesn't make sense for a male that is attracted to females to leave a club full of females and go outside where there are lots of males. There are females to be had!
  35. D

    What may be the negative catalyst?

    The reaction between sodium carbonate and calcium chloride gives the table salt and calcium carbonate. The reaction takes place immediately after mixing two solutions. Can anyone suggest me how the reaction can be slowed down? Thank in advance Peace Deb
  36. K

    Confused on what should be negative when finding with half angle identities

    Homework Statement The question is to find sin 2x, cos 2x, tan 2x from the given information: sin x = -\frac{3}{5}, x in Quadrant III Homework Equations Half Angle Identities cos2x = cos^{2}x - sin^{2}x sin2x = 2sinxcosx tan2x = \frac{2tanx}{2-tan^{2}x} The Attempt at a...
  37. 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...
  38. B

    Coulomb's law and negative charges

    Homework Statement see attachment Homework Equations The Attempt at a Solution Do you see the step where they go from (1.35keq2)/a2 to 1.91keq2)/a2 ? I can't get that step. To my mind. If you square 1.35 then take its square root, you get 1.35 not 1.91
  39. C

    Negative acceleration, deceleration and decreasing acceleration

    What is the difference between decreasing acceleration, deceleration and negative acceleration? Most importantly, i want to clarify that acceleration is the rate of change of velocity over time, it Does not necessarily mean that the car velocity is increasing and that a car is speeding up when...
  40. JJBladester

    Rate of entropy generation (can it be negative?)

    Homework Statement The Clausius inequality combined with the defintion of entropy yields an inequality known as the increase of entropy principal, expressed as Sgen ≥ 0 where Sgen is the entropy generated during a process. Homework Equations Sgen ≥ 0 The Attempt at a Solution...
  41. J

    Don't you hate negative questions?

    Ummm. Let me think.
  42. idir93

    Can the spring constant k be negative ?

    Can the spring constant "k" be negative ? Hi, I found a difficulty when solving this problem from my textbook : In the arrangement of Figure 7-11 (which is basically a standard block attached to spring resting horizontally), we gradually pull the block from x = 0 to x = +3.0 cm, where it is...
  43. A

    What is negative energy and how does it relate to the capacity for work?

    If the positive energy is the capacity to perform work what about the negative energy?
  44. S

    Significance of Negative Frequency

    Hi Just wanted to know if negative frequency has any significance? Thanks Salil
  45. O

    Negative distance? Can it be real?

    I started wondering about this after solving a problem on the exam. Here is the problem: 2 planes has a speed v1 and v2. They are flying from the airport at the same time. The difference between their landings on the same airport is t. Express the distance between the airports as functions of...
  46. H

    Negative diagonal elements in Incomplete Cholesky Decompostion

    Dear all, I'm facing a problem in performing incomplete Cholesky decomposition of sparse matrices. I use the algorithm which avoids talking square roots, given in here: http://en.wikipedia.org/wiki/Cholesky_decomposition and apply it to sparse matrices by just skipping the zeros ( no...
  47. G

    How does negative feedback in an op-amp work conceptually.

    Consider an op-amp in which there is a DC voltage of 100mV for example applied to the non-inverting (positive) terminal of the op-amp and the negative terminal of the op-amp is connected to the output directly. Also take the voltage supplied to power the op-amp, Vcc, to be 15V and the gain, A...
  48. O

    How to determine the positive or negative charge?

    Red is for + and Black is for -. If I place red rod into positive side of battery and place black rod into negative side of battery, it displays +9V. If my hand is touching the black rod, and the red rod is touching the ground, then it displays a negative value, I would like to know...
  49. G

    Negative Energy in Particles: A Conundrum

    I'm kind of struggling with the concept of energy. A particle in a conservative field has kinetic and potential energy (E=T+U), but I can always choose an inertial frame where the motion of the particle is zero, which means I can change the the particle's kinetic energy by just switching frames...
  50. B

    Negative times negative is positive?

    Probably the stupidest question I have ever asked, but is it possible to prove that the multiplication of two negatives yields a positive? Go easy on me I've asked better questions :D BiP
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