Answer
$0\le f\lt 60Hz$
Work Step by Step
We know that
$I_{rms}\lt 1mA$
But $I_{rms}=\omega C\times V_{rms}$
$\implies \omega CV_{rms}\lt 1mA$
We plug in the known values to obtain:
$(2\pi f\times 0.22\times 10^{-6}\times 12)\lt (1\times 10^{-3})$
$\implies f\lt \frac{1\times 10^{-3}}{2\pi\times 0.22\times 10^{-3}\times 12}$
This simplifies to:
$f\lt 60.2Hz$
Thus, the required range of the frequency is $0\le f\lt 60Hz$
