  In this paper we investigate a solution of the Dirac equation for a
spin-$\frac{1}2$ particle in a scalar potential well with full spherical
symmetry. The energy eigenvalues for the quark particle in $s_{1/2}$ states
(with $\kappa=-1$) and $p_{1/2}$ states (with $\kappa=1$) are calculated. We
also study the continuous Dirac wave function for a quark in such a potential,
which is not necessarily infinite. Our results, at infinite limit, are in good
agreement with the MIT bag model. We make some remarks about the sharpness
value of the wave function on the wall. This model, for finite values of
potential, also could serve as an effective model for the nucleus where $U(r)$
is the effective single particle potential.
