Ring Definition and 1000 Threads

  1. STEMucator

    Ring Theory: Solving Homework Statement with Double Inclusion Method

    Homework Statement Didn't know what to title this one. I found it while I was doing some practice problems : http://gyazo.com/51a668d4db1a1638353a9de4b43d42ed Homework Equations lcm(m,n) = k for some integer k. The Attempt at a Solution I'm not really sure how to start this...
  2. A

    Questions about Proving R/I is not the Zero Ring

    I have a question about the proof that I attached... 1) Since R/I is not the zero ring, we know that 1 \not= 0. What is the reason to say 1 + I \not= 0 + I instead of 1 \not= 0?2) Also, how do we compute something like (a+I)(b+I)? Isn't this correct (a+I)(b+I) = ab+aI+bI+I^2? 3) Finally, if we...
  3. A

    A question about ring homomorphisms

    Homework Statement If R is a domain with F=Frac(R), prove that Frac(R[x]) is isomorphic to F(x). Homework Equations The Attempt at a Solution Let \phi : Frac(R[x]) \rightarrow F(x) be a map sending (f(x),g(x)) to f(x)/g(x). We need to show that \phi is a ring homomorphism. Let f,g,h,k be in...
  4. S

    Solving the Olympic Ring Puzzle: Calculate Max Mass

    Homework Statement This is the diagram http://s1302.beta.photobucket.com/user/Rameel17/media/dd_zps43d04d44.png.html A single large circular Olympic ring hangs freely at the lower end of a strong flexible ring which is firmly supported at the other end. Two identical beads each has a mass...
  5. A

    A question about ring homomorphisms

    I attached a page from my textbook, because there was something that I didn't understand. What I don't understand is in the proof it says let f(x) be...etc. but in the theorem, it says nothing about f(x). In other words, where in the thoerem does it say anything about f(x). Why are they...
  6. L

    Infinite ring with exactly two non trivial maximal ideals

    Hey! Is there an infinite ring with exactly two maximal ideals. Thanks in advance LiKeMath
  7. D

    Induced current on a metallic ring

    I've just got confused about how the induced current in a metallic ring is calculated. Consider a metallic ring (radius a, resistance R and inductance L) immersed in a oscillating magnetic field, which is oriented orthogonally to the plane of the ring. The variation in flux of magnetic...
  8. R

    How to build a speaker using an SMD audio (ring) oscillator?

    Hi! I aim to use a piezoelectric wafer and get it to work as a loudspeaker by supplying it with a fluctuating voltage withing the audible region. I know this can be done using a simple DC to AC invertor/oscillator circuit, but the challenge is to build it as small as possible. I looked up...
  9. A

    Derive an Equation for Period of Ring Pendulum

    Homework Statement Apply the physical pendulum equation to a ring pivoted on its edge to derive the equation for the period of a ring pendulum for small oscillations about the pivot point. Include a diagram showing the restoring torque acting on a ring pendulum displaced from equilibrium...
  10. Fantini

    MHB Does R/N Form a Ring with Unity if N is a Proper Ideal of R?

    Good afternoon. Here is the problem: Show that if $R$ is a ring with unity and $N$ is an ideal of $R$ such that $N \neq R$, then $R/N$ is a ring with unity. My answer: Consider the homomorphism $\phi: R \to R/N$. Given $r \in R$ we have that $\phi(r) = r + N = \phi(1 \cdot r) = \phi(r \cdot 1)...
  11. Fantini

    MHB Quotient Ring of a Field: Is it Trivial or Isomorphic to the Field?

    Good afternoon! Along the same lines as the other, here is the question: Show that the quotient ring of a field is either the trivial one or is isomorphic to the field. My answer: Let $N$ be an ideal of the field $F$. Assume that $N \neq \{ 0 \}$. Consider the homomorphism $\phi: F \to F / N$...
  12. Fantini

    MHB Is Every Homomorphism of a Field to a Ring One-to-One or Null?

    Good afternoon! I wasn't able to get the necessary grade in abstract algebra and now I'm redoing many exercises and I would like some correction. All help is appreciated! (Smile) Here is the question: Show that every homomorphism of a field to a ring is one-to-one or null. Let $\phi: F \to R$...
  13. camilus

    Product and intersection of ideals of polynomial ring

    Let k[x,y,z,t] be the polynomial ring in four variables and let I=<x,y>, J=<z, x-t> be ideals of the ring. I want to show that IJ=I \cap J and one direction is trivial. But proving I \cap J \subset IJ has stumped me so far. Anyone have any ideas?
  14. Adoniram

    Gravitational Potential of a ring, at a point P

    Homework Statement I am asked to calculate the gravitational potential of the ring at the point Q. I can do this for point P, but Q is killin me... Homework Equations V = GM/r M = ρ2∏a dM = ρadθ radius of ring = a The Attempt at a Solution Well for the case at point P, it...
  15. P

    Toy car moving in a horizontal ring.

    Hi, I sincerely hope one of you could please help me with the equations in the following problem. Homework Statement A toy car is forced to move along a circular ring placed on a table with no friction. The friction coefficient between the ring and the car is given as μ. At t=0 the car...
  16. O

    Ring Terminal Connections for Harsh Environments

    I'm working on a project that uses solenoids for mechanical activation. The solenoids have lugs for the + and - electrical connections. I am connecting my wires to the lugs with ring terminals. The problem I have is that the product will be subject to outdoor, harsh environmental...
  17. P

    Magnet moved through copper ring

    Homework Statement The figure shows a ring of copper with its plane perpendicular to the axis of the nearby rod-shaped magnet. For each of the situations described below, indicate whether there will or will not be a current induced in the ring and justify your reasoning, drawing pictures if...
  18. I

    Find the emf induced in a metal ring rotating in a magnetic field

    First off, sorry if this is a simple question, I'm very bad at electromagnetism. Homework Statement A metal ring of radius R rotates with constant angular velocity ω about a diameter. Perpendicular to the rotation axis is a constant magnetic induction field \underline{B}. Find the EMF...
  19. Square1

    Prove the set of integers is a commutative ring with identity

    How should one prove that the integers form a commutative ring? I am not sure exactly where to go with this and how much should be explicitly shown. A ring is meant to be a system that shares properties of Z and Zn. A commutative ring is a ring, with the commutative multiplication property...
  20. F

    Ring of Charge, Electric Potential

    Homework Statement A proton is moving along the main axis of a uniformly charged thin ring. The charge density on the ring is 5.0nC/cm and the ring radius is 1.0cm. Initially the proton is 2.0cm (along the axis) from the center of the ring with the velocity towards the center of the ring. What...
  21. Z

    Proton moving towards center of ring

    Homework Statement A proton is moving along the main axis of a uniformly charged thin ring. The charge density on the ring is 5.0 nC / cm and the ring radius is 1.0 cm. Initially the proton is 2.0 cm (along the axis ) from the center of the ring with the velocity towards the center of the...
  22. H

    Ideal in Matrix Ring Z36 | Counting Matrices

    Homework Statement Consider the ring of 3x3 matrices over the ring Z36.How many different matrices are there in the two sided ideal generated by the matrix diag(0,-6,18)?Homework Equations The Attempt at a Solution I computed a general matrix in the two sided ideal,but counting is complicated...
  23. A

    Intuition for Quotient Ring in Polynomials

    I just had a discussion with someone who said he thought about quotient rings of polynomials as simply adjoining an element that is a root of the polynomial defining the ideal. For example, consider a field, F, and a polynomial, x-a, in F[x]. If we let (x-a) denote the ideal generated by x-a...
  24. K

    Moment that is affecting a ring

    Homework Statement A 20 A current is flowing through a ring. Ring's diameter is 30 cm. What is the value of the Moment that is affecting the ring? Homework Equations The Attempt at a Solution
  25. A

    Show ring ideal is not principal ideal

    Homework Statement Show that the ideal (3, x^3 - x^2 + 2x -1) \text{ in } \mathbb{Z}[x] is not principal. (The parentheses mean 'the ideal generated by the elements enclosed in parentheses') 2. The attempt at a solution I came up with a solution (see attachment), it is just rather...
  26. P

    Related Rates involving circular ring

    Homework Statement A circular ring of wire of radius r0 lies in a plane perpendicular to the x-axis and is centered at the origin. The ring has a positive electric charge spread uniformly over it. The electric field in the x-axis direction, E, at the point given by E=kx/((x^2 +r0^2)^(3/2))...
  27. A

    Ring Homomorphism: unit in R implies unit in R'

    I was just looking at wikipedia's article on ring homomorphisms (http://en.wikipedia.org/wiki/Ring_homomorphism) and I am a little confused. If you look at the definition they give for ring homomorphism, they require only that addition and multiplication is preserved over the homomorphism...
  28. L

    Quotient of the Mutlplicative Monoid of a Ring

    In abstract algebra (ring theory specifically), when we are dealing with factorization, UFD's, and so on, we are often only interested in the multiplicative structure of the ring, not the additive structure. So here is the basic situation we face: we a start with an integral domain (R,+,*)...
  29. R

    Expectation value of z component of angular momentum for a particle on a ring

    I have to find the expectation value of the z component of the angular momentum for a particle on a ring and the expectation value of the z component of the angular momentum squared for a particle on a ring. The wavefunction is e^((± imx)) I've determined that the expectation value for the...
  30. C

    What Is a Fuel Gas Ring Main in Benzene Production?

    Aparently the fuel gas is used for the heater in the production of benzene from toluene. But once this, it goes to the fuel gas ring main which I have no clue of what it is! Help :)
  31. A

    What does it mean for a Ring to be Stabilized by a map

    Homework Statement Let D be a division ring, C its center and let S be a division subring of D which is stabilized by every map x -> dxd-1, d≠0 in D. Show that either S = D or S is a subset of C. 2. The attempt at a solution I haven't actually started working on it yet because I am not...
  32. H

    Motion of a particle in a verticle ring.

    See attachment the green spot shows the initial position of a particle the blue spot shows the position at which the particle loses contact with the ring. Intuitively one can easily deduce that the particle would indeed loose contact with the ring. Is there a way to prove this...
  33. Z

    Finding work to move a point charge to the center of a thin ring.

    1. Find the work required to move a point charge from infinitely far away to the center of a thin ring. The point charge is q= 1nanocoulomb. The rings charge is Q= 2 nanoC. The ring has a radius r=2m.Homework Equations U= qV W= -U Thoughts I think the first thing to consider is the field E...
  34. Spinnor

    Repeling particles on a ring, minimum angular momentum.

    Say we have two particles of mass m which repel each other, V = V(seperation). Let these particles be constrained to move on a circle of radius r. The particles want to stay at opposite sides of the circle because they repel each other. We want to treat this as a quantum problem so the particles...
  35. M

    Wave going to a massless ring on a pole

    Hello, I was reading my textbook and watching MIT Opencourseware and noticed a discrepancy between the two. There was a string attached to a massless ring on a pole without friction, on the MIT website it said the ring will go twice the amplitude of the wave, but in the textbook it said it...
  36. E

    What is the contradiction in the proof for M/I\subseteqJ/I and M\subseteqJ?

    Homework Statement I am curious, if I,J, and M are ideals of the commutative ring R, and M/I\subseteqJ/I, then M\subseteqJHomework Equations M/I = { m+I : m is in M} J/I = { j+I : j is in J} I\subseteqR is an ideal if 1.) if a and b are in I then a+b is in I 2.) if r is in R and a is in I...
  37. N

    Charged ring with oscillating particle

    Homework Statement A ring of radius 6 cm that lies in the yz plane carries positive charge of 7 μC uniformly distributed over its length. A particle of mass m carrying a charge of −7 μC executes small oscillations about the center of the ring on its axis with an angular frequency of 15...
  38. Fantini

    MHB Prove Unique Identity in Ring: Solution Explained

    Hello everybody. Here's the problem: $$\text{Let } R \text{ be a ring with identity. Let }a \in R \text{ and suppose that exists an unique } a' \in R \text{ such that }a a' =1. \text{ Prove that } a'a=1.$$ My solution: Since we have an identity, it has an inverse (itself), which means we can...
  39. E

    Moment Of Inertia of broken disk or ring confusion

    We all know that M.I of a Uniform rigid rod about an axis perpendicular to it's length and passing through it's center is MLsquare/12.Where M is mass and L is length of the rod. If it is broken to half such that M becomes M/2 and L becomes L/2,we can't apply ML square /12 formula to it.We have...
  40. C

    Find magnitude of a force on a ring.

    Homework Statement http://session.masteringengineering.com/problemAsset/1127430/5/Probs.2-83_84.jpg Refer to image for problem. I have to find the magnitude of the force F3. I'm stuck on where to begin. Homework Equations Don't know. The Attempt at a Solution I've done...
  41. V

    Quantum degeneracy problem, electron on a ring

    Homework Statement Homework Equations Below The Attempt at a Solution So this is a lot like the infinite square well, except periodic. If S is an arc length, then S = \theta R so \frac{d^2}{dS^2} = \frac{1}{R^2}\frac{d^2}{d\theta^2}, which is more convenient to use in the hamiltonian. So...
  42. R

    Gaussian integers, ring homomorphism and kernel

    Homework Statement let \varphi:\mathbb{Z}[i]\rightarrow \mathbb{Z}_{2} be the map for which \varphi(a+bi)=[a+b]_{2} a)verify that \varphi is a ring homomorphism and determine its kernel b) find a Gaussian integer z=a+bi s.t ker\varphi=(a+bi) c)show that ker\varphi is maximal ideal in...
  43. S

    What is the general approach for calculating tension in different situations?

    Hello people, So i found out the tension in a ring rotating with constant angular velocity (in gravity free space) Considering a small element of mass dm - tension will provide the centripetal force, 2Tsin(dθ/2) = dmrω^2 sindθ ≈ dθ dm = m/2πr ds ds = rdθ T = (mrω^2)/2πNow, the other method...
  44. R

    Slip Ring Crane duty motor related issue

    Hello , I have a 60kW hoisting motor with 600 rpm ,10 pole ,crane duty slip ring motor When the motor is started for its hoisting operation through resistance motor starts slow and immediately goes into full rpm having no sign of resistance. Does anyone know what might be the reason...
  45. F

    Find Period of rotation of the copper ring in a Magnetic Field

    Homework Statement A Copper Ring with Radius r and mass m hangs by a thread and rotates with a period T. Ring's coefficient of self inductance is L . What would be a new rotation period of ring, if it was in a horisontal uniform magnetic B field, which is parallel to Ring's plane on a...
  46. J

    Computation Question in the Ring of Polynomial with Integer Coefficients

    I have a quick question. The problem reads: Prove that there is no integer m such that 3x2+4x + m is a factor of 6x4+50 in Z[x]. Now, Z[x] is not a field. So, the division algorithm for polynomials does not guarantee us a quotient and remainder. When I tried dividing 6x4+50 by 3x2+4x +...
  47. J

    Quick question on the characteristic of a ring.

    I was looking back at a proof I did a while ago. Suppose na=0 with n≠0 and a≠0. Then n is a multiple of the characteristic. I supposed p < n is our characteristic, then I simply used the divison algorithm (I divided n by p) and the distributive property which lead to the remainder being 0. From...
  48. G

    Calculating Young's Modulus for a Ring Chain of Springs

    I know that Young's modulus for a spring is Y= K*L/A where K: is the stiffness of the spring L: the original length of the spring A: the cross sectional area How does this formula change in the case of continuously distributed springs over a ring chain of radius R and a...
  49. P

    How much HP to spin this ring?

    OK I'm super frustrated.. I spent 50min typing the whole text here earlier and click preview only to be told I was logged out. Click back and and all was gone. Damn.. Ok here's the question, AGAIN. Weight: 1kg Type: Flywheel, OD is 80mm, ID is 40mm if that matters. So that's a typical...
  50. W

    Electric field of a ring and beads

    Homework Statement a plastic ring of radius R = 50.4 cm. Two small charged beads are on the ring: Bead 1 of charge +2.00 μC is fixed in place at the left side; bead 2 of charge +6.00 μC can be moved along the ring. The two beads produce a net electric field of magnitude E at the center of the...
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