A magneto‐fluid dynamic flow interaction in the shock tube flow of an electrically conducting test gas over a cone aligned with an applied magnetic field was experimentally observed, whereRM = 0.25. For the variable applied field up to 0.9 W/m2, the maximumIa = 0.50, andAvaried from greater than to less than unity. Gas dynamic flow changes were not observed, but the measured unsteady induced magnetic field data effectively illustrated the role of diffusion in the propagation of the fast and slow magnetoacoustic waves. In addition, the direct observation of the fast magnetoacoustic wave was a very significant result.