What was used to detect the radio waves?

$A$ parallel plate capacitor of area $A = 16 \ cm^2$ and separation between the plates $10 \ cm$ is charged by a $DC$ current. Consider a hypothetical plane surface of area $A_0 = 3.2 \ cm^2$ inside the capacitor and parallel to the plates. At an instant,the current through the circuit is $6 \ A$. At the same instant,the displacement current through $A_0$ is . . . . . . $mA$.

The displacement current through the plates of a parallel plate capacitor of capacitance $30 \mu F$ is $150 \mu A$. The capacitor is charged by a source of varying potential at the rate of: (in $Vs^{-1}$)

The electric field through an area of $2 \ m^2$ varies with time as shown in the graph. The greatest displacement current through the area is at $t = ..... \ \mu s$.

You are given a $2 \,\mu F$ parallel plate capacitor. How would you establish an instantaneous displacement current of $1 \, mA$ in the space between its plates?

In Hertz's experiment,the rods act as a/an ...... .