We have developed a simple computer code that simulates the electromagnetic response of a simplified magnetosphere with respect to pressure variations at the magnetopause. The dependence of the magnetospheric response on the azimuthal wave number of the magnetopause perturbation and possible effects of a kinetic correction to the Alfv¿n wave dispersion are investigated. We find that the coupling of the cavity mode to Alfv¿n oscillations is most efficient for wave numbers m=1⋅⋅⋅3. With increasing wave number, the fundamental cavity mode may lower its eigenfrequency, opposed to the behavior of the higher-order modes. Kinetic effects cause a propagation of Alfv¿n wave energy away from the resonant field line. ¿American Geophysical Union 1987