Displacement current

A displacement current of 4.0 A can be set up in the space between two parallel plates of 6 μF capacitor. The rate of change of potential difference across the plates of the capacitor is nearly $\alpha\times10^6$ V/s. The value of $\alpha$ is ________.

The displacement current of 4.425 $\mu$A is developed in the space between the plates of parallel plate capacitor when voltage is changing at a rate of $10^6$ Vs$^{-1}$. The area of each plate of the capacitor is 40 cm$^2$. The distance between each plate of the capacitor is $x\times10^{-3}$m. The value of $x$ is ______

(Permittivity of free space, $E_0=8.85\times10^{-12}$ C$^2$ N$^{-1}$ m$^{-2}$)

The rms value of conduction current in a parallel plate capacitor is 6.9 $\mu$A. The capacity of this capacitor, if it is connected to 230 V ac supply with an angular frequency of 600 rad/s, will be :