Task id9629

The space between the plates of a flat capacitor is filled with a dielectric. At a certain potential difference between the plates, the energy of the capacitor is W = 2 • 10-5 J. After the capacitor was disconnected from the voltage source, the dielectric was removed from the capacitor. In this case, it was necessary to perform work A = 7 • 10-5 J against the forces of the electrostatic field. Find the dielectric constant of the dielectric.