Effects of Hall current on unsteady hydromagnetic free convection flow with heat and mass transfer of an electrically conducting, viscous, incompressible and time dependent heat absorbing fluid past an impulsively moving vertical plate in a porous medium, in the presence of thermal diffusion is studied. Exact solution of governing equations is obtained in closed form by Laplace Transform technique. Exact solution is also obtained in case of unit Prandtl number and unit Schmidt number. Expressions for skin friction due to primary and secondary flows and Nusselt number for both ramped temperature and isothermal plates are also derived. Expression for Sherwood number is also derived. The numerical values of primary and secondary fluid velocities, fluid temperature, and fluid concentration are displayed graphically whereas that of skin friction and Nusselt number are presented in tabular form for various values of pertinent flow parameters. Free convection flow with heat and mass transfer near a ramped temperature plate is compared with free convection flow with heat and mass transfer near an isothermal plate.
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