|We use grid-adaptive numerical simulation by independently solving one dimensional radiative hydrodynamic equations of hundreds of magnetic lines uniformly selected from a sheared magnetic arcade configuration. Depending on magnetic strength, all of these magnetic lines undergo steady and finite-time chromospheric heating. We combine these evolved magnetic lines back to a three dimensional sheared arcade to investigate the formation and subsequent evolution of a normal polarity prominence. Synthetic emission count rates of Atmospheric Imaging Assembly at extreme ultraviolet wavelengths are calculated from simulation data. As a result, a coronal-cavity-like structure is found in our shear magnetic arcade configuration based simulation. So, we suggest that corona cavity in observation is not definitely correspond to a flux rope. For a normal polarity prominence held by sheared magnetic arcade, cavity is also present.