A particle with a specific charge $q = 10^8$ C/kg flies into the Wilson chamber located in a magnetic field with induction $B = 10^{-2}$ T. The direction of its velocity is perpendicular to the magnetic field lines. After the velocity vector is rotated by $90$ degrees (the change in the particle's track radius was $\varepsilon = 5 \%$) the field is switched off. After that the particle travels the path $s = 300$ mm to a complete stop.