Flux through a Paraboloid

    • group Scalar Surface and Volume Elements

      group Small Group Activity

      30 min.

      Scalar Surface and Volume Elements
      AIMS Maxwell AIMS 21 Static Fields Winter 2021

      Integration Sequence

      Students use known algebraic expressions for length elements \(d\ell\) to determine all simple scalar area \(dA\) and volume elements \(d\tau\) in cylindrical and spherical coordinates.

      This activity is identical to Vector Surface and Volume Elements except uses a scalar approach to find surface, and volume elements.

    • assignment Find Area/Volume from $d\vec{r}$

      assignment Homework

      Find Area/Volume from \(d\vec{r}\)
      AIMS Maxwell AIMS 21 Static Fields Winter 2021

      Start with \(d\vec{r}\) in rectangular, cylindrical, and spherical coordinates. Use these expressions to write the scalar area elements \(dA\) (for different coordinate equals constant surfaces) and the volume element \(d\tau\). It might help you to think of the following surfaces: The various sides of a rectangular box, a finite cylinder with a top and a bottom, a half cylinder, and a hemisphere with both a curved and a flat side, and a cone.

      1. Rectangular: \begin{align} dA&=\\ d\tau&= \end{align}
      2. Cylindrical: \begin{align} dA&=\\ d\tau&= \end{align}
      3. Spherical: \begin{align} dA&=\\ d\tau&= \end{align}

    • assignment Cone Surface

      assignment Homework

      Cone Surface
      AIMS Maxwell AIMS 21 Static Fields Winter 2021

      Using integration, find the surface area of a cone with height \(H\) and radius \(R\). Do this problem in both cylindrical and spherical coordinates.

    • assignment Zapping With d 1

      assignment Homework

      Zapping With d 1
      Energy and Entropy Fall 2020 Energy and Entropy Fall 2021

      Find the differential of each of the following expressions; zap each of the following with \(d\):

      1. \[f=3x-5z^2+2xy\]

      2. \[g=\frac{c^{1/2}b}{a^2}\]

      3. \[h=\sin^2(\omega t)\]

      4. \[j=a^x\]

      5. \[k=5 \tan\left(\ln{\left(\frac{V_1}{V_2}\right)}\right)\]

    • assignment Gauss's Law for a Rod inside a Cube

      assignment Homework

      Gauss's Law for a Rod inside a Cube
      AIMS Maxwell AIMS 21 Consider a thin charged rod of length \(L\) standing along the \(z\)-axis with the bottom end on the \(x,y\)-plane. The charge density \(\lambda_0\) is constant. Find the total flux of the electric field through a closed cubical surface with sides of length \(3L\) centered at the origin.
    • assignment Current from a Spinning Cylinder

      assignment Homework

      Current from a Spinning Cylinder
      A solid cylinder with radius \(R\) and height \(H\) has its base on the \(x,y\)-plane and is symmetric around the \(z\)-axis. There is a fixed volume charge density on the cylinder \(\rho=\alpha z\). If the cylinder is spinning with period \(T\):
      1. Find the volume current density.
      2. Find the total current.
    • assignment Sphere in Cylindrical Coordinates

      assignment Homework

      Sphere in Cylindrical Coordinates
      AIMS Maxwell AIMS 21 Find the surface area of a sphere using cylindrical coordinates.
    • assignment Gravitational Field and Mass

      assignment Homework

      Gravitational Field and Mass
      AIMS Maxwell AIMS 21

      The gravitational field due to a spherical shell of matter (or equivalently, the electric field due to a spherical shell of charge) is given by: \begin{equation} \vec g = \begin{cases} 0&\textrm{for } r<a\\ -G \,\frac{M}{b^3-a^3}\, \left( r-\frac{a^3}{r^2}\right)\, \hat r & \textrm{for } a<r<b\\ -G\,\frac{M}{r^2}\, \hat r & \textrm{for } r>b \\ \end{cases} \end{equation}

      This problem explores the consequences of the divergence theorem for this shell.

      1. Using the given value of the gravitational field, find the divergence of the gravitational field everywhere in space. You will need to divide this question up into three parts: \(r<a\), \(a<r<b\), and \(r>b\).
      2. Discuss the physical meaning of the divergence in this particular example.
      3. For this gravitational field, verify the divergence theorem on a sphere, concentric with the shell, with radius \(Q\), where \(a<Q<b\). ("Verify" the divergence theorem means calculate the integrals from both sides of the divergence theorem and show that they give the same answer.)
      4. Discuss how this example would change if you were discussing the electric field of a uniformly charged spherical shell.

    • assignment Electric Field and Charge

      assignment Homework

      Electric Field and Charge
      divergence charge density Maxwell's equations electric field AIMS Maxwell AIMS 21 Consider the electric field \begin{equation} \vec E(r,\theta,\phi) = \begin{cases} 0&\textrm{for } r<a\\ \frac{1}{4\pi\epsilon_0} \,\frac{Q}{b^3-a^3}\, \left( r-\frac{a^3}{r^2}\right)\, \hat r & \textrm{for } a<r<b\\ 0 & \textrm{for } r>b \\ \end{cases} \end{equation}
      1. Use step and/or delta functions to write this electric field as a single expression valid everywhere in space.
      2. Find a formula for the charge density that creates this electric field.
      3. Interpret your formula for the charge density, i.e. explain briefly in words where the charge is.
    • group Vector Surface and Volume Elements

      group Small Group Activity

      30 min.

      Vector Surface and Volume Elements
      AIMS Maxwell AIMS 21

      Integration Sequence

      Students use known algebraic expressions for vector line elements \(d\vec{r}\) to determine all simple vector area \(d\vec{A}\) and volume elements \(d\tau\) in cylindrical and spherical coordinates.

      This activity is identical to Scalar Surface and Volume Elements except uses a more sophisticated vector approach to find surface, and volume elements.

  • AIMS Maxwell AIMS 21 Static Fields Winter 2021

    Find the upward pointing flux of the electric field \(\vec E =E_0\, z\, \hat z\) through the part of the surface \(z=-3 s^2 +12\) (cylindrical coordinates) that sits above the \((x, y)\)--plane.