% Author: Prof. Dr. Matthias Jung, DL9MJ
% Year: 2024
\begin{tikzpicture}
    % Define a formula for the coil.
    % This is what the numbers mean:
    % A ... how far the rings are apart
    % B ... how much from the side the rings are seen (try 0 and the same as the radius)
    % C ... radius of the rings
    \def\coil#1{
        % A                   B
        {0.3 * (2*#1 + \t) + 0.55*sin(\t * pi r))},
        % C
        {1.0 * cos(\t * pi r)}
    }

    % Draw the rectangle
    \draw[thick] (0,-0.60) to [open, name={n1}] (3.75,0.80);

    \draw[thick](n1) ++(-0.15,0) node[
        cylinder,
        draw=black,
        cylinder uses custom fill, 
        cylinder body fill = black!10, 
        cylinder end fill = black!40,
        aspect=3.0,
        minimum width = 1.4cm*\getDarcImageFactor,
        minimum height = 4.25cm*\getDarcImageFactor
    ](c){};

    % Draw the part of the coil in front of the rectangle
    \foreach \n in {0,1,...,5} {
        \draw[domain={0.7:2.2},smooth,variable=\t,samples=15, thick]
            plot (\coil{\n});
    }

    \draw[domain={ 0.0:0.5},smooth,variable=\t,samples=15,thick] plot (\coil{6});
    \draw[domain={-0.5:0.2},smooth,variable=\t,samples=15,thick] plot (\coil{0});
    \draw[thick] (-0.7,0) coordinate(start) to [short,-o] (-0.7,-2);
    \draw[thick] (4.3,0) coordinate(end) to [short,-o] (4.3,-2);

    \DARCmeasure{start}{end}{0,1.25}{0}{$l$}
    \draw[Triangle-](c.east) ++(-0.2,0) -- ++(1,-1) node[anchor=north west](){$A$};
    \draw(c.south) ++(0,-0.75) node[](){$N$};
\end{tikzpicture}