\documentclass[12pt]{article}
\usepackage{graphicx, multicol,wrapfig,exscale,epsfig,fancybox,fullpage}
\pagestyle{empty}

\parindent=0pt
\parskip=.1in

\newcommand\hs{\hspace{6pt}}

\begin{document}

\centerline{\textbf{Calculating Total Charge}}
\bigskip

For each case below, find the total charge.  What are the dimensions of the 
constants $\alpha$ and $k$? 
(If the total charge is infinite, what should you calculate instead to provide 
meaningful information?)

\begin{enumerate}
\item A positively charged (dielectric) spherical shell of inner radius $a$ 
and outer radius $b$ with a spherically symmetric internal charge density 
$\rho (r) = \alpha r^{3}$

\vfill
\item A positively charged (dielectric) spherical shell of inner radius $a$ 
and outer radius $b$ with a spherically symmetric internal charge density 
$\rho (r) =3 \alpha e^{(kr)^{3}}$

\vfill
\item A positively charged (dielectric) spherical shell of inner radius $a$ 
and outer radius $b$ with a spherically symmetric internal charge density 
$\rho (r) = \alpha \frac{e^{(kr)}}{r^{2}}$

\vfill
\item A positively charged (dielectric) cylindrical shell of inner radius $a$ 
and outer radius $b$ with a spherically symmetric internal charge density 
$\rho (s) = \alpha s^{3}$

\vfill
\item A positively charged (dielectric) cylindrical shell of inner radius $a$ 
and outer radius $b$ with a spherically symmetric internal charge density 
$\rho (s) =3 \alpha e^{(ks)^{2}}$

\vfill
\item A positively charged (dielectric) cylindrical shell of inner radius $a$ 
and outer radius $b$ with a spherically symmetric internal charge density 
$\rho (s) = \alpha \frac{e^{(ks)}}{s}$

\end{enumerate}
\vfill
\end{document}