Lag1989 problem №19.31

The coil, whose inductance L = 30 μH, is connected to a flat capacitor. The area of each plate is S = 100 cm2, the distance between them is d = 0.1 mm. Determine the dielectric constant of the medium that fills the space between the plates, if the contour resonates on a monochromatic electromagnetic wave, whose length is 750 m.