Transit times of excited atoms in a dc arc plasma exposed to an inhomogeneous magnetic field are investigated at different values of the magnetic induction. At the optimal value, the transit time, electron pressure and spectral line intensities are maxima. The large increase of spectral line intensity is not proportional to the slight increase of transit time. The transit times of different atoms at the same value of the magnetic induction are approximately equal, whereas the spectral line intensities are different. The maximum transit time corresponds to minimum electron mobility. The arc-plasma temperature is directly proportional to the magnetic induction.