Plasma flow to an obstacle is examined using the two‐fluid equations. In this model the obstacle is assumed to be a two‐dimensional strip that extends to infinity in theydirection (slab geometry). An obstacle inserted into a magnetized plasma will cast a ‘‘shadow’’ along the magnetic field lines. The natural collection length of such an obstacle is a measure of the length of its shadow. This study shows that in a typical fusion tokamak, wherecs/&OHgr;cid≪1 (&OHgr;ci,csare the ion cyclotron frequency and the ion acoustic speed, respectively,dis the half‐width of the strip), the particle collection length of an obstacle can be approximated asL∥=0.23csd2/D⊥, ifD⊥/csd≪1; or 0.30d, ifD⊥/csd≫1. For the cases examined in this study, the inclusion of the electron–ion collisional drag parallel toB0changes the solution only by an insignificant amount.