A parallel-plate capacitor has square plates of length l l\,l separated by distance d d\,d and is filled with a dielectric.
A second capacitor has square plates of length 4l separated by distance 2d 2d\,2d and has air as its dielectric.
Both capacitors have the same capacitance.
What is the relative permittivity of the dielectric in the first capacitor?
18\frac{1}{8}81
222
444
888
