How can I center the text vertically in my table?

Question

How can I center the text vertically in my table?

In the followong example "Number" and "Potential" are not centered vertically

Example:

\documentclass[fleqn, listof=totoc, bibliography=totoc, a4paper, fontsize=12pt, headsepline, oneside, openright]{scrbook}
\usepackage{xcolor}
\usepackage{booktabs,colortbl,tabularx}

\setlength{\aboverulesep}{0pt}
\setlength{\belowrulesep}{0pt}
\setlength{\extrarowheight}{.75ex}

\begin{document}

\begin{table}[H]
\centering
\caption{caption}
\label{tab:potential}
\begin{tabular}{cc}

\toprule
\rowcolor{lightgray}
Number & Potential \\
\midrule
01& 681 $\mu{}m$\\
02& 688 $\mu{}m$\\
03& 702 $\mu{}m$\\
04& 716 $\mu{}m$\\
05& 701 $\mu{}m$\\
06& 815 $\mu{}m$\\
\bottomrule

\end{tabular}
\end{tab

Answer 1

Don't use extrarowheight. As there's no \extrarowdepth, it won't be vertically centred. U used the cellspace package, which defines minimal vertical padding at the top and bottom of cells in columns with specifiers prefixed with the letter S, or C if you load siunitx – which I did, as the symbols for micrometers should be in upshape font. Also I took the liberty to change your grey to a nicer (for me) shade of grey. B.t.w., if you load xcolor with option [table], you don't have to load colortbl:

\documentclass[fleqn, listof=totoc, bibliography=totoc, a4paper, fontsize=12pt, headsepline, oneside, openright]{scrbook}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[table, svgnames]{xcolor}
\usepackage{booktabs,tabularx, float}
\usepackage{siunitx}

\setlength{\aboverulesep}{0pt}
\setlength{\belowrulesep}{0pt}
\usepackage{cellspace}
\setlength\cellspacetoplimit{6pt}
\setlength\cellspacebottomlimit{6pt}

\begin{document}

\begin{table}[H]
  \centering
  \caption{caption}
  \label{tab:potential}
  \begin{tabular}{CcCc}
    \toprule
    \rowcolor{Lavender!75!lightgray}
    Number & Potential     \\
    \midrule
    01     & \SI{681}{\um} \\
    02     & \SI{688}{\um} \\
    03     & \SI{702}{\um} \\
    04     & \SI{716}{\um} \\
    05     & \SI{701}{\um} \\
    06     & \SI{815}{\um} \\
    \bottomrule
  \end{tabular}
\end{table}

\end{document}