Spherical Shell Step Functions

  • step function charge density
  • Static Fields 2021

    One way to write volume charge densities without using piecewise functions is to use step \((\Theta)\) or \(\delta\) functions. Consider a spherical shell with charge density \[\rho (\vec{r})=\alpha3e^{(k r)^3} \]

    between the inner radius \(a\) and the outer radius \(b\). The charge density is zero everywhere else.

    1. (2 pts) What are the dimensions of the constants \(\alpha\) and \(k\)?
    2. (2 pts) By hand, sketch a graph the charge density as a function of \(r\) for \(\alpha > 0\) and \(k>0\) .
    3. (2 pts) Use step functions to write this charge density as a single function valid everywhere in space.