The displacement current of $4.425 \mu\mathrm{A}$ is developed in the space between the plates of parallel plate capacitor when voltage is changing at a rate of $10^6 \mathrm{~V~s}^{-1}$. The area of each plate of the capacitor is $40 \mathrm{~cm}^2$. The distance between each plate of the capacitor is $x \times 10^{-3}$ m. The value of $x$ is $\_\_\_\_$. (Permittivity of free space, $\varepsilon_0 = 8.85 \times 10^{-12} \mathrm{~C}^2 \mathrm{~N}^{-1} \mathrm{~m}^{-2}$)