Answer:
[tex]Q=55.5 \mu C[/tex]
Explanation:
We start by writing the formula of the energy stored between two charged parallel plates, which is:
[tex]U=\frac{Q^2}{2C}[/tex]
Where Q is the charge on one of the plates and C its capacitance, which for two parallel plates is:
[tex]C=\frac{\epsilon A}{d}[/tex]
Where A is the area of each plate, d the distance between them and [tex]\epsilon[/tex] the permittivity of the medium, in our case the vacuum, [tex]\epsilon_0[/tex].
Putting all together:
[tex]U=\frac{Q^2d}{2\epsilon_0 A}[/tex]
Which means:
[tex]Q=\sqrt{\frac{U2\epsilon_0 A}{d}}[/tex]
Which for our values is:
[tex]Q=\sqrt{\frac{(11\times10^3J)2(8.85\times10^{-12}F/m)(0.000019m^2)}{(0.0012m)}}=55.5\times10^{-6}C[/tex]
