# Align the n's in the equation

In the following code, how do I align the n's?

Here is the MWE:

\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
n \propto exp(-U/kT) \notag \\
\Rightarrow \quad n  = A.exp(-U/kT) \notag
\end{align}
\end{document}


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Something like this. Put & right after n's.

Update: commented by barbara beeton. Thanks.

Code

\documentclass[12pt]{article}
\usepackage[paper size={10cm,3cm}]{geometry}
\usepackage{amsmath}
\begin{document}
\begin{align}
n& \propto \exp(-U/kT) \notag \\
\Rightarrow \quad n&  = A \exp(-U/kT) \notag
\end{align}
\end{document}

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I would change \Rightarrow to \implies. – Manuel Jul 19 '14 at 10:27
@Manuel -- Thanks for the suggestion, mcuh appreciated. A link tex.stackexchange.com/q/47063/34618 for the OP to make his/her decision. – Jesse Jul 19 '14 at 10:51
the exp should really be roman. \exp is already provided by amsmath as an operator name, which should do the right thing. – barbara beeton Jul 19 '14 at 13:24
@barbarabeeton -- Much appreciated. Corrected accordingly. – Jesse Jul 19 '14 at 13:28
\documentclass[preview,border=12pt,12pt]{standalone} % please change it back to your article class below
%\documentclass[12pt]{article}
\usepackage{amsmath}

\begin{document}
\abovedisplayskip=0pt\relax% don't use this line in your production
\begin{align*}
n                   & \propto \exp(-U/kT)  \\
\Rightarrow \quad n &= A \exp(-U/kT)
\end{align*}
\end{document}


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What is the difference between this and Jesse's answer? – Manuel Jul 19 '14 at 10:27
@Manuel This answer makes the alignment at the proportional and equals signs, rather than at the ns, which is standard practice: if the relations didn't have the same RHSs, the difference would be more noticeable. – ChrisS Jul 19 '14 at 10:48
@Manuel: \exp and exp is one of the differences. – kiss my armpit Jul 19 '14 at 10:56
@ChrisS And so does Jesse's. Pleasedon'ttouch true, I missed that one ;) – Manuel Jul 19 '14 at 10:56