\magnification=\magstep3

$$
   { {\rm Prob}(x_0 < x < x_0 + dx)} = { {|\Psi(x_0)|}^2 dx }
$$

$$\eqalign{
   { {\rm Prob}(r_0 < r < r_0 + dr)} &= { {|\Psi(r_0)|}^2 dV } \cr
                                     &\phantom{=} \cr
                                     &= { {|\Psi(r_0)|}^2 r^2 dr } \cr
}
$$

$$
   { {\rm Prob}(R_1 < r < R_2)} = { {\int_{R_1}^{R_2}} {{|\Psi(r)|}^2 r^2 dr}  } 
$$


$$
  E  =  - {{\hbar^2} \over{2 m a^2}}  =  
         - {{ {m_e}^2 e^4} \over{32 \pi^2 {\epsilon_0}^2 \hbar^2 }} 
$$




\bye
