Eigenvalue bounds for a positive semidefinite matrix

Question

I have a symmetric $(p\times p)$, positive semi definite matrix $\Omega$. If somebody says: find the eigenvalue bounds of the matrix such that $$w_1I \le \Omega \le w_2I$$ where $I$ is the identity matrix, how can I find $w_1$ and $w_2$? I already know what $\Omega$ is.