The energy stored in a capacitor is given by
[tex]U= \frac{1}{2} CV^2[/tex]
where C is the capacitance and V the voltage applied.
In our problem, [tex]C=0.900 \mu F=0.9 \cdot 10^{-6} F[/tex], while the energy is [tex]U=1.5 j[/tex]. We can then solve the formula to find V:
[tex]V= \sqrt{ \frac{2U}{C} }= \sqrt{ \frac{2\cdot 1.5 J}{0.9\cdot 10^{-6} F} }=1826 V [/tex]
