otranslate nohighlight">\(r\)</span>:</p>
<div class="math notranslate nohighlight">
\[F_\theta = -q (\ddot r B_z -\dot z B_r) =\frac {d} {rdt} (\gamma m r ^ 2\dot\theta).\]</div>
<p>The flow penetrating the area covered by a circle of radius $ r $, the center of which is located on the axis, and it passes through the point at which the charge is located, is written in the form <span class="math notranslate nohighlight">\(\psi =\int\limits ^ r_0 2\pi r B_z dr\)</span> . When a particle moves by <span class=