# Problem in typing a symbol

I want to type this character as a symbol for energy:

But when I type capital u, it is shown as:

• Can you please add an MWE? Perhaps you have loaded a font package that changes the normal font of the document. Try with: \documentclass{article}\begin{document}$U$\end{document} and see if that works. – manooooh Dec 12 '18 at 1:30
• You have selected a different font than the default, hence you get a different capital U. – Henri Menke Dec 12 '18 at 1:41

If you want U from the default Computer Modern font you can just define it using another name. I used \energy because that is what you want to use it for.

\documentclass{article}

% Change the main math font
\usepackage{mathpazo}

% Get Computer Modern U'' back under different name
\DeclareSymbolFont{cmletters}{OML}{cmm}{m}{it}
\DeclareMathSymbol{\energy}{\mathalpha}{cmletters}{U}

\begin{document}

$U \energy$

\end{document}
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