Afuel gauge uses a capacitor to determine the height of the fuel in a tank. the effective dielectric constant keff changes from a value of 1 when the tank is empty to a value of k, the dielectric constant of the fuel, when the tank is full. the appropriate electronic circuitry can determine the effective dielectric constant of the combined air and fuel between the capacitor plates. each of the two rectangular plates has a width w and a length l (fig. p24.68). the height of the fuel between the plates is h